Class Video from Fall 2017
Click on the date below to view the lecture video. NOTE: It will take 30 seconds or so to load the video. If you are on a connection off campus, it may take longer. I recommend viewing the videos while you are on campus.
The video for this class will be posted between 20 hours and 36 hours following the class.
The video for this class will be posted between 20 hours and 36 hours following the class.
Today we continued discussing and practicing drawing simple Lewis structures. We learned about double bonds and triple bonds in Lewis structures. Electronegativity (BCE25) was introduced, as the tendency of atoms sharing electrons in a covalent bond to attract electrons to themselves. The higher the electronegativity the higher the tendency to attract electrons. Electronegativity values help assign central atoms (low electronegativity) and terminal atoms (high electronegativity). We discovered that some molecules/polyatomic ions required more than one Lewis structure to accurately represent the arrangement of electrons. Such examples required resonance structures to represent their Lewis structure. We also introduced Formal Charge on an atom. Formal charge (on an atom) = # of valence electrons - 0.5 of the bonding electrons - # of lone pair electrons. A formal charge of zero is optimal. Checkout ACA27 and BCE26.
We looked a orbital shapes and and then discussed ionic bonds and lattice energy as a measure of the strength of an ionic bond (electrostatic attraction between oppositely charged ions). Next we discussed covalent bonds (the sharing of electrons by the overlap of atomic orbitals). We discussed Lewis structures and I started drawing Lewis structures for some simple compounds.
We began class with a verbal review of the first ionization energy periodic trends (periodicity) that was discussed in class on Thursday, November 9th. Next we discussed atomic radii trends across a period from left to right and down a group from top to bottom. The explanation of these trends parallel the trend in first ionization energy. Next we discussed successive ionization energies on a single atom. Effective nuclear charge was introduced (ENC). Z*eff = Z - # of inner core electrons. We applied this ENC calculation on the valence electron (n=3) in magnesium, and also on the second electron ionized in magnesium and the third electron ionized in magnesium (which is removed from the n=2 level). Successive ionization energies increase as electron-electron repulsions decrease. Then we discussed ionic radii for metal ions compared to metal atoms and ionic radii for nonmetal ions compared to nonmetal atoms. Near the end of class we discussed ionic compounds, by revisiting how to assign ionic compounds from the compounds formula. The concept of lattice energy was introduced as a measure of the strength of an ionic bond. We looked at lattice energy data to determine trends in lattice energies for ionic compounds.
We began class with some review of Tuesday's lecture, We next looked at the electron arrangment animation to see how electrons are distributed in the multi-electron atom. We looked at exceptions (Cr and Cu) in the first transition metal series. Then we discussed the trend in first ionization energy going across a period from Left to right. We look at the figure in our lecture notes on ionization energy that describes the first ionization energies for the first ten elements. Next we discussed the trend in first ionization energy going down a group from top to bottom and how to explain the trend. Going down a group the first ionization energy decreases. This is due to the fact that the valence electron is in a higher shell (going down a group), which is higher in energy, and threfore would require less energy to remove. Next we discussed two exceptions in the general trend of increasing 1st ionization energy going across a period. Specifically we discussed the 1st IE for beryllium compared to boron, and then nitrogen compared to oxygen.
We reviewed the shape of the periodic table and discussed how the periodic table indicates the shell and subshell that an atom's electron occupy. We discussed electron spin and how that property, combined with the number of electrons in a subshell could give rise to the concept of an orbital. In our model of the atom orbitals can hold a maximum of two electrons, with opposite spin. We next looked at the electron arrangment animation to see how electrons are distributed in the multi-electron atom.
Thursday, November 2, 2017
No class on this date
We discussed an activity to develop how Coulomb's Law can help interpret ionization energy data to invent the concept that electrons occupy different shells. Electrons in 'Shells' have energy and a distance from the nucleus. The ionization energy provides the evidence that there are two electrons in the first shell, eight electrons in the second shell, and so far eight electrons in the third shell (although there are actually eighteen electrons in the third shell). Shells are labeled with values of 1, 2, 3, 4 etc up to infinity, the variable we associate with theses electronic shells is 'n'.
We discuss wave properties, frequency, wavelength, speed of light and energy using several mathematical relationships. We practiced using some of those relationships.
We discussed Exam II. Next we discussed enthalpy and calculating the enthalpy change for new reactions using Hess' Law. We did several examples. If you are looking for the DCI for the class it is linked Week 9, Tuesday, October 17, 2017 in the During Class section.
Thursday, October 19, 2017
No class
We discussed the BCE where we had added an ionic solid, NaOH, to water. Both were at the same temperature, yet when they were mixed the temperature of the solution increased. We talked about what caused that and we agreed it was the dissolution process of the NaOH dissolving in water. We wrote a first law mathematical equation for that as (qdissolution = - qsolution). In the BCE problem we are interested in calculating qdissolution. So we used the equation qdissolution = - msolution*specific heatsolution*delta Tsolution to calculate qdissolution. Then when divided by the moles of solute we determine the heat flow at constant pressure which is called delta H (the change in enthalpy) in kJ/mol. Next we did another calorimetry problem from the DCI workbook on page 41 which involved calculating the delta H for a neutralization reaction between a stong acid and a strong base.
We discussed the ACA and to review the first law of thermodynamics in terms of who loses heat and who gains heat. We discussed the heat transfer in terms of hot and cold water (qhot water = - qcold water) and in terms hot piece of metal and cold water (qhot metal = - qcold water).
We worked on the first law of thermodynamics. We invented that q(heat) was proportional to mass time the change in temperature. To make this proportionality an equality we added a constant. We call the constant specific heat. q(heat) = mass * specific heat * 
T. We have done several problems mixing hot and cold water so we looked at tow examples from the DCI workbook on adding a hot piece of metal to cold water. Based on the first law of thermodynamics we set up a mathematical equation to describe how heat flowed (from a hot object to a cold object). Next we substituted for q(hot) and q(cold) and developed a relationship which we substituted know quantities to solve for either the specific heat of the metal, or the final temperature of a mixture.
We spent more than half of the class reviewing solution stoichiometry/limiting reagent problem using ICE tables. We also summarized the five different ypes of chemical reactions that everyone should be aware of. After the review we started discussing the BCE that students did fantastic. There is considerable excellent intuition about the relationship between heat, amount of substance and change in temperature. So after discussing the BCE we did a set of clicker questions were we moved from a qualitative understanding to a quantitative discussion. We ended class with inventing that q(heat) was directly proportional to the mass of substance times its change in temperature.
In this class we began with several clicker questions on predicting the products for a double replacement reaction, and for recognizing a net ionic equation. We continued with our discussion of neutralization reactions and single replacement reactions. We practiced writing ionic and net ionic equations. Next I defined molarity and we looked at the BCE, and discussed some of those problems. I then did a demonstration of how to prepare a 0.200 M CuSO4 solution of using a 100 mL volumetric flask and solid CuSO4.5H2O and distilled water. After preparing that solution I demonstrated prepared 100 mL of 0.0200 M CuSO4 solution by dilution.
We began discussing double replacement reactions by first introducing a Solubility Table. We need a Solubility Table to be able to determine the phases of the products of double replacement, neutralization and single replacement reactions. After writing the formulas of the products of a double replacement reaction and assigning the phase of each product we practiced writing the ionic and net ionic equations. We did several examples. Near the end of class we started working on neutralization reactions.
We began class with a limiting reagent clicker question. We worked through the ICE table for the particular problem to practice using ICE tables with limiting reagent problems. Next we did some additional stoichiometry problems to practice interpreting the wording of a problem and how we would use the ICE table to determine the amounts of products and reactants. Near the ened of class we started discussing double replacement reactions. We looked at a video of a double replacement reaction to help us write the products and to see the important feature(s) of double replacement reactions.
We practice doing ICE tables and stoichiometry problems for all of class by working through the stoichiometry activity that was available on our Personal Page.
We began the class with a clicker question using moles. The question is a very typical kind of question that requires grams to mol conversion, mol to number of formula units/molecules and molecules to number of atoms. Next we did a sample problem using combustion analysis data to determine the empirical formula of a hydrocarbon. We also discussed the relationship between an empirical molar mass and a molecular molar mass. Finally we finished out the class looking a some particulate level diagrams and writing chemical equations. Then we introduced an ICF table to help track all of the information going on in a chemical reaction. We talked about excess reagent and limiting reagent.
In today's class we spent the beginning of class discussing the first exam results. Next we discussed formulas, specifically empirical, simplest and molecular formulas of compounds. We did an example of determining the formula of a compound given weight percent data. We also discussed the importance of significant figures, and mol ratios and when to round and when not to round.
In today's class we discussed the atomic mass of the elements in the periodic table. We focused on the meaning of the atomic mass, depending on the units for the atomic mass. We introduced the concept of the mol and its two definitions: 1 mol = 6.023 x 1023 and the molar mass of a substance. We worked on some problems in the During Class Inventions workbook.
In today's class we worked one more problem from the DCI Workbook using the RWAAM equation. The problem was similar to PS2.7, in that we were given the RWAAM and the isotopic masses of the isotopes, but not the fractional abundance. Working the problem was good practice for PS2.7. Following that we spent the remaining time doing nomenclature. We covered considerable material, so be sure to print out the powerpoint for thursday's class so you can practice naming compounds.
In today's class we discussed two clicker question in detail. The first clicker question related to adding numbers expressed in scientific notation and the second clicker question related to weight percent and density of solutions. Next we did an activity where we invented a relationship between isotopic mass, fractional abundance and relative weighted average atomic mass. we did one problem using the relationship.
In class today we reviewed the ACA and did several clicker questions over significant figures, rounding, calculations using significant figures and conversions. Be sure to practice so that you feel more confident about this material. Try problems at the end of the Chapter 1 in Tro.
We began with a clicker question that summarized some memorization that students need to do for the first exam. Memorize the formula and the standard state phase for all of the elements in the periodic table. Also be sure you can spell the names of the first 20 elements and additional common elements. The spelling is important for an upcoming lecture on naming compounds. Next we discussed chemical change and we looked at containers with particulate level models of elements and compounds. Based on a a pair of diagrams we wrote a chemical equation, and then discussed that chemical equations show formulas of elements and/or compounds, and coefficients represent the ratio in which reactants react and products are formed. Next we reviewed ACA2 and then BCE2. We discussed significant figures, rounding, significant figures in calculations, and practiced with a few conversions. We covered DCIs on page 3 - 10.
We used the Classification of Matter activity from the During Class Inventions and Computer Lab Activities workbook to categorize the contents of the twenty containers depicting matter at the particulate level. The categories that students came up with included: pure substance or mixture; gas, liquid or solid; atoms or molecules; elements or compounds; heterogeneous or homogeneous mixture. We mentioned diatomic molecules. We also discussed physical and chemical change as demonstrated in different containers.
This was 'syllabus' day. We discussed class policies (see the General Information Page), exam dates (see the Syllabus) and reviewed the class website. Also checkout the Powerpoint used in lecture.
This was 'syllabus' day. We discussed class policies (see the General Information Page), exam dates (see the Syllabus) and reviewed the class website.
We used the Classification of Matter activity from the During Class Inventions and Computer Lab Activities workbook to categorize the contents of the twenty containers depicting matter at the particulate level. The categories that students came up with were: pure substance or mixture; gas, liquid or solid; atoms or molecules; elements or compounds; heterogeneous or homogeneous mixture. We also heard diatomic molecules. We also discussed physical and chemical change as demonstrated in different containers.
Today we reviewed BCE1, ACA2 and BCE2. From BCE1 we focused on density as determined from a particulate level diagram, and also interpreting what phase the particulate level diagram depicted. From ACA2 we focused on using particulate level diagrams in representing chemical equations. We learned about parts of a balanced chemical equation: that is, the reactants and products are always represented as formulas of elements or compounds (so I asked everyone to memorize the formula of every element in the periodic table); that coefficients represent the ratio which reactants react and products are formed (and that the coefficients are NOT amounts of reactants and/or products); and finally that we can not place identical formulas of substances on both sides of a chemical equation (we will discuss how we handle excess amounts in a few weeks). In BCE2 we focused on significant figures and significant figures in calculations and conversions. We discovered that many students had diffficulty with Q3b, Q3c and Q4c. We will discuss conversions in more detail on Thursday.
We reviewed significant figures in calculations as there were severl examples that students found to be challenging, so we discussed additional examples. We talked about conversions by looking at ACA3. Again students were successful with those conversions that were straight-forward, but found converting area or density units to be more difficult. We discussed examples of each. Near the end of class we started looking at the chemical formula as a symbolic representation of an element or compound. We discussed water, H2O, and how that formula communicated that there are two hydrogen atoms and one oxygen atom in the compound AND there are NO H2molecules.
We discussed the ACA on density for a few minutes and than moved to the BCE to discuss the mass and charge of the electron, proton and neutron. Then we discussed isotopes, atoms of an element with the same number of protons, but a different number of neutrons. We discussed the mass number (# protons + # neutrons); the atomic number (# protons) and the charge (#protons + # electrons). Students were successful on simple isotopes in the second row, but were not as successful with elements with larger atomic numbers. Students have difficulty determining the number of electrons. Next we did the DCI on inventing the weighted average mass of a set of marbles. We invented the RWAAM (relative weighted average atomic mass) equation for summing the product of the isotopic mass times the fractional abundance of a number of isotopes. We did several different types of problems using the RWAAM equations.
After a clicker question on RWAAM and a brief discussion on the ACA from Tuesday's class we discussed nomenclature for ionic and covalent compounds.
We began the discussion with a review of the ACA from Thursday's class. Overall students were doing a good job writing chemical formulas (see the ACA6 results on your Personal ACA page, near the bottom). Next we discussed synthesis reactions to produce ionic or covalent compounds. A synthesis reaction has two elements in their standard state forming a compound. For ionic compounds we can use the principle of electroneutrality to arrive at the correct formula for the product. For covalent compounds the formula has to be known, since covalent compound formulas do not follow 'simple' patterns. The phase of all ionic compounds, in CHEM 1314, is solid. For covalent compounds the phase must be known since the phase could be gas, liquid or solid. Next we introduced hydrocarbons and combustion reactions. Combustion reaction have a hydrocarbon and oxygen as reactants. Combustion reactions between hydrocarbons and oxygen form carbon dioxide gas and liquid water. We practiced balanccing both type of reactions. Next we discussed the mass of one formula unit of a substance in units of amu's and grams, and the mass of 1 mol of a substance in grams. Avogadro's number (6.022 x 1023)was introduced and we did several sample calculations using the relationship between moles and molar mass and moles and Avogadro's number. BCE6 and BCE7 have additional sample problems using these ideas/relationships.
We reviewed the first exam via a set of clicker questions and discussed some aspects of the questions on the exam. Remember the Exam V in CHEM 1314 includes questions from the content covered by the first three exams. If you struggled with a particular content covered on any of the first three exams, that content is likely to be part of Exam V. Next we reviewed ACA7 and discussed moles and did several calculations using moles. We then started discussing percent composition and determined the percent composition of the elements in Na2S2O3. We then used the percent composition data to determine the empirical formula of the same compound. Next we looked at some different data that could be used to determine the empirical formula of the compound.
We began class with a clicker question: given a particulate level diagram identify the best balanced chemical equation. We discussed the ACA on the determination of an empirical formula given percent composition data, or combustion analysis. Based on the results students had a good grasp of using percent composition dat to determine the empirical formula. We then discussed the similarity of data from cobustion analysis and percent composition. We did several sample calculations of how to determine the mass of carbon, given the mass of carbon dioxide produced when a sample of a hydrocarbon is combusted. That calculation was related to the calculation of the mass of hydrogen determined from the mass of water produced in the combustion analysis. Next looked at the results of the clicker questions, but we did not discuss them specifically. Instead we looked at Q2 on page 25 of the DCI/CLA workbook and students were asked to draw the contents of a container given the balanced chemical equation. (Just the opposite of the clicker question). We discussed several different students responses and related the drawings to the balanced chemical equation. We then re-did the clicker question we'd started class with. This time we did discuss the results. There was a movement away from a popular wrong aanswer from the first clicker question. Next we looked at a simulation written by a former undergraduate at OSU that depicted the reaction between two diatomic elements to produce a compound. From the simualtion we determined the balanced chemical equation, and who was a limiting reagent and who was in excess, and then ICE tables were introduced as a way to track the (I)nitial, (C)hange and (E)nding amounts of the reactants and products. Next we looked at Q4 on page 30 of the DCI/CLA workbook and looked at part a. We will pick up from there on Thursday.
We started class with several cclicker questions again focusing on how we read a balanced chemical equation and how the Change row relates to the coefficients in the balanced chemical equation. In class we focused on using ICE tables to solve stoichiometry problems. We finished off the problems on page 30 in the DCI Workbook and then did several other types of problems.
We began with a review of stoichiometry problems with a clicker questions. The clicker question asked for the limiting reagent in the reaction between hydrogen and oxygen to form water. Masses of hydrogen and oxygen were given. So we worked through the clicker question to determine the mass of water produced. We then looked at another stoichiometry problem in ACA11 and worked through that example. SO we have done about 15 stoichiometry problems using the ICE table. Next we started discussing three new reactions. The three reactions are double replacement, neutralization and single replacement. We briefly reviewed synthesis and combustion reactions, and then started discussing double replacement reactions. We looked a double replacement reaction movie, linked to Tuesday's Assignment page. We then wrote the baalnced chemical equation. To assign the solubility of each of the products we looked at a Solubility Table and learned how to read that table. We did several more double replacement reactions, predicting products, writing formulas and identifying the phase of the products. We ended class talking about ionic equation and net ionic equation.
In this class discussion focused on writing molecular, ionic and net ionic chemical equations for double replacement, neutralization and single replacement reactions. Be sure to review lecture notes from Tuesday, September 20, 2016 over this material. For neutralization reactions you are responsible for recognizing who are the strong acids and who are the weak acids. For our purposes the strong acids are HCl, HBr, HI, HNO3, H2SO4 and HClO4. All other acids in the lecture notes list are weak. For Exam II the only weak acid I will hold you responsible for will be acetic acid, HC2H3O2. There are other weak acids on PS5 that you must work with however. You are also responsible for recognizing who are the strong bases and who are the weak bases. Any metal hydroxide, M(OH)x, is a strong base, while the only weak base you will be responsible for on exam II will be ammonia, NH3.
We reviewed ACA13. Students were doing great on identifying ions from formulas of ionic compounds. Next we discussed the five types of reactions that everyone would be responsible for. We classified each by the nature of the reactants. I also asked about what the reaction was on PS5.1b. No one could identify the type of reaction until the end of class, but this is an important reaction that I will expect you to know. We also wrote the molecular, ionic and net ionic equations for a weak acid and strong base neutralization reaction. Next we talked about the BCE briefly, and then I prepared a solution of copper(II) sulfate in water using a 100 mL volumetric flask, I then diluted 10.00 mLs of that solution using another 100 mL volumetric flask. We did the calculations to determine the molarity of the original solution and also the moalarity of the diluted solution. We ended class by beginning a stoichiometry problem that would produce a solution of NaOH. We will finish the problem at the beginning of the next class.
We spent about half of the class reviewing solution stoichiometry/limiting reagent problem using ICE tables. We also summarized the five different ypes of chemical reactions that everyone should be aware of. After the review we started discussing the BCE that students did fantastic. There is considerable excellent intuition about the relationship between heat, amount of substance and change in temperature. So after discussing the BCE we did a set of clicker questions were we moved from a qualitative understanding to a quantitative discussion. We ended class with inventing that q(heat) was directly proportional to the mass of substance times its change in temperature.
We briefly reviewed the ACA from Thursday's class to identify some challenges students were having. Important *If you are having difficulty answering questions on an ACA or BCE those are likely questions on an upcoming exam.* Checkout the bottom of the ACA Page or the BCE Page for links that provide summary information on how well students are answering most questions on an ACA or BCE. We continued with our discussion of heat flow and the first law of thermodynamics. We invented that q(heat) was proportional to mass time the change in temperature. TO make this proportionality an equality we added a constant. We call the constant specific heat. q(heat) = mass * specific heat * T. We have done several problems mixing hot and cold water so we looked at tow examples from the DCI workbook on adding a hot piece of metal to cold water. Based on the first law of thermodynamics we set up a mathematical equation to describe how heat flowed (from a hot object to a cold object). Next we substituted for q(hot) and q(cold) and developed a relationship which we substituted know quantities to solve for either the specific heat of the metal, or the final temperature of a mixture.
We began class by discussing the second exam, how hard, how was the time, and what was your 'favorite question'. Next we discussed the ACA and to review the first law of thermodynamics in terms of who loses heat and who gains heat. We discussed the heat transfer in terms of hot and cold water (qhot water = - qcold water) and in terms hot piece of metal and cold water (qhot metal = - qcold water). Next we discussed the BCE where we had added an ionic solid, NaOH, to water. Both were at the same temperature, yet when they were mixed the temperature of the solution increased. We talked about what caused that and we agreed it was the dissolution process of the NaOH dissolving in water. We wrote a first law mathematical equation for that as (qdissolution = - qsolution). In the BCE problem we are interested in calculating qdissolution. So we used the equation qdissolution = - msolution*specific heatsolution*delta Tsolution to calculate qdissolution. Then when divided by the moles of solute we determine the heat flow at constant pressure which is called delta H (the change in enthalpy) in kJ/mol. Next we did another calorimetry problem from the DCI workbook on page 41 which involved calculating the delta H for a neutralization reaction between a stong acid and a strong base.
We began class with several clicker questions over the specific first law mathematical equation that is appropriate for particular types of questions that we had addressed in the DCI Workbook. Next we did Question3 in the DCI workbook which was a bomb calorimeter type of problem. We started the problem with a clicker question on the first law mathematical equation, and then finished the problem. In this problem we calculated the change in internal energy (heat flow at constant volume). Next talked about ethalpy (heat flow at constant pressure) and discussed the BCE for the day. Next we loooked at the PowerPoint to discuss how we could use the enthalpy for two chemical reactions to determine the enthalpy change for a new chemical reaction.
In this class we finished up discussing the first law of thermodynamics with a discussion of the ethalpy of formation and how with enthalpy's of formation it is possible to calculate the enthalpy for a reaction.
I was absent for this class and Eric covered for me. He introduced wavelength, frequency, amplitude and energy for waves. He did several sample problems from the DCI workbook.
In this class we began a review of the relationship between wavelength and frequency for a photon of light, and given the frequence how to calculate the enegy of a photon of light. Next we looked an activity where we reviewed ionization energy data and by applying Coulomb's law we developed a mode of an atom and its electrons described by an energy level diagram. This model explained the ionization energy data in terms of electrons occupying shells. The first shell has 2 electrons, the second shell has 8 electrons, and the third looked like it had 8, but as we later learn the third shell has 18 electrons. We left class with the new model of the electronic structure of the atom. However, we were not through with developing the model. More on Thursday.
During this class we began with a review of the energy level diagram for a hydrogen atom and discussed the equation that allowed the calculation of the energy for each level. We disscuss the mathematical calculation to determine the energy of a photon absorbed or released when an electron moved between two energy levels. Next we discussed photoelectron spectroscopy and look at PES data for the first 18 atoms. We interpreted that data and determined that in any shell (after the n=1 shell) there are electrons with different energies. So we invented the idea that within a shell there are subshells. Shells are labeled with numbers, 1, 2, 3, 4.... and subshells are labeled with letters; s, p, d, f,... We wrote several electron configurations for different elements in the periodic table. Next we were beginning to look at a new form of an energy level diagram. The energy level diagram we discussed at the beginning of class on shows levels. The new one will show levels, sublevels and orbitals.
We reviewed the shape of the periodic table and discussed how the periodic table indicates the shell and subshell that an atom's electron occupy. We discussed electron spin and how that property, combined with the number of electrons in a subshell could give rise to the concept of an orbital. In our model of the atom orbitals can hold a maximum of two electrons, with opposite spin. We next looked at the electron arrangment animation to see how electrons are distributed in the multi-electron atom. We looked at exceptions (Cr and Cu) in the first transition metal series. At the end of lecture we looked at the experimental trend in ionization energy across a period and discussed how we can explain the overall increase in IE when going from left to right. We also discussed the two exceptions to this rule.
We began class with some review of Tuesday's lecture, when we discussed the trend in first ionization energy going across a period from Left to right. We look at the figure in our lecture notes on ionization energy that describes the first ionization energies for the first ten elements. Next we discussed the trend in first ionization energy going down a group from top to bottom and how to explain the trend. Going down a group the first ionization energy decreases. This is due to the fact that the valence electron is in a higher shell (going down a group), which is higher in energy, and threfore would require less energy to remove. Next we discussed removing more than one electron from the same atom. In this case we must consider the shell value for each electron removed. The higher the shell value of the electron, the higher the energy of the electron, and the lower the energy to ionize. To help make that connection effective nuclear charge was introduced (ENC). Z*eff = Z - # of inner core electrons. We applied this ENC calculation on the valence electron (n=3) in sodium, and also on the second electron ionized in sodium (which is removed from the n=2 level). Next we discussed atomic and ionic radii trends for elements and for ions.
We looked a orbital shapes and and then discussed ionic bonds and lattice energy as a measure of the strength of an ionic bond (electrostatic attraction between oppositely charged ions). Next we discussed covalent bonds (the sharing of electrons by the overlap of atomic orbitals). We discussed Lewis structures and I started drawing Lewis structures for some simple compounds.
Eric discussed Lewis structures of compounds with single, double and triple bonds, as well as formulas where resonance structures are required to adequately describe the molecule or polyatomic ion. He discussed formal charge for an atom and how to determine its value. Formal charge is very important in assigning relative importance for different resonance structures.
We contined the discussion of Lewis structures, resonance structures, bond order, formal charge and electronegativity.
We began with a review of Lewis structures, formal charge and determining the number of bonding domains and nonbonding domains on a central atom. We reviewed electronegativity to help explain covalent bonds as either polar or nonpolar. We then considered molecules with more than two atoms to see when molecules were polar or nonpolar. That decision would be based on the molecular geometry of the compound. So we looked at Valence Shell Electron Pair Repulsion theory to help predict molecular geometry and bond angles made by sets of three atoms. We discussed the molecular geometry and bond angles for central atoms with two, three, four, five and six domains of electrons.
In this lecture the ACA was reviewed. Next we looked more closely at the bonding in HF, NH3 and H2O. We began by considering the 2p atomic orbitals on F, N and O that overlap with the 1s atomic orbital on H. While the overlapping atomic orbitals worked for HF, there were some issues with NH3 and H2O. In the case of H2O using 2p atomic orbitals on O to overlap with the 1s atomic orbital on H produced an H2O with H-O-H bond angles of 90 degrees. The experimental H-O-H bond angle in H2O is 105.5 degrees. The same issue arises for NH3. Predicted H-N-H bond angles of 90 degrees when using 2p atomic orbitals on N and 1s atomic orbitals on H do not match the experimental H-N-H bond angle of 107 degrees. So we modified our model of atomic orbital overlap on the central atom by mixing 2s and 2p atomic orbitals to produce sp3, sp2 and sp hybrid orbitals. We found that sp3 hybrid orbitals could be used to explain the molecular geometry when four domains of electrons are on the central atom. sp2 hybrid orbitals could be used to explain the molecular geometry when three domains of electrons are on the central atom. sp hybrid orbitals could be used to explain the molecular geometry when two domains of electrons are on the central atom. We also were able to better understand the nature of a double and triple bond. We saw the in a double bond sp2 hybrid orbitals overlapped to form a sigma bond and 2p atomic orbitals overlapped to produce the pi bbond. Double bonds are composed of two bonds, a sigma type bond and a pi type bond. This lecture used several animations to depicted the formation of hybrid orbitals from atomic orbitals, and the formation of double and triple bonds.
Today we focused on ideal gases. We began with several clicker questions to determine the relationship between pressure and three other variables; volume, temperature and mol of gas. From this we arrived at the ideal gas law equation PV=nRT. We practiced using the relationship in single-value problems, change of condition problems and stoichiometry problems.
Today's class focus on questions asked by students. Those questions began with hybrization and the nature of the atomic or hybrid orbitals involved in forming covalent bonds. Next questions from PS14 were addressed. Specifically we discussed problems PS14.3e and PS14.8.
Class Video from Fall 2015
This was the first lecture of the semester and we discussed the structure of the course, grading, and the class web site.
After answers some student questions we discuss matter in terms pure substances and mixtures. We discussed elements, compounds, atoms, molecules, mixtures in terms of particulate diagrams. We also discussed physical and chemical changes. Everyone was left with the task of having to draw a particulate diagram in the DCI activity.
We began with a clicker question regarding memorizing the phase and formulas for the elements in the periodic table. We then looked at BCE#1 to discuss particulate level view of water, and the difference in the solid and liquid phases. Next we discussed ACA#2 for the class. In Q3 it was interesting that a majority of students felt the best equation to describe the chemical reaction was 4SO2 + 5O2 --> 4SO3 + 3O2. There were two errors in that logic. First O2 can not be both a reactant and a product, second coefficients do not represent how many of each particle are present. We also discussed the chemical equation for the reaction between Na(s) and Cl2(g). We then discussed parts of the BCE#2. We reviewed significant figures (look at lecture notes for Thursday, August 20, 2015). We also discussed significant figures in calculations. Near the end of class we started discussing conversions by looking at the first conversion problem in BCE#2. The class has a good grasp of significant figures, but had difficulty reporting result of calculations to the correct number of significant figures.
We began by doing several clicker questions. The questions covered addition of numbers expressed in scientific notation and converting cubed units. We then discussed ACA#3 Q2c. We then discussed conversion and tried a few conversion questions. Based on the ACA results over 75% of students can do the very straightforward conversion questions. So we discussed the more complex conversions. Students were having difficulty with density units. We also discussed the density activity in BCE#3. We ended lecture discussing the Ionic and covalent compounds and how to write formulas for ionic compounds.
We started with a clicker question on determining the number of protons, neutrons and electrons in an isotope of an element. Then we discussed atomic number, atomic mass and mass number. We discussed the units on the atomic mass and the definition of the atomic mass unit. We discussed isotopes and then developed the relative weighted average atomic mass for an element and did a calculation. We discussed variations on equation used to calculate RWAAM. We covered the DCI on pages 11 - 14 in the DCI workbook. We ended class discussing nomenclature of simple ionic compounds.
We began with a clicker question calculating the frational abundance for two isotopes of element Z. We discussed parts ACA#5 and BCE#5 and reviewed some common errors in naming compounds or writing formulas that contain polyatomic ions. We discussed naming binary covalent compounds, and acids. We also mentioned compounds that contained ammonium ions. We discussed synthesis and combustion reactions and how to predict products for those reactions and how to balance equations. Lots of good examples in Problem Set #3. Be sure to try the nomenclature DCI activities. At the end of class we discussed atomic mass units, and introduced Avogadro's number. (We covered a lot of material!!)
Class began with a discussion of the BCE for the day's class. We did several clicker questions. We discussed moles, molar mass, and Avogadro's number. We did several different types of questions using moles.
We began with a clicker question covering the first exam. The consensus was the exam was hard but there was enough time to complete the exam. More information about the exam will be forthcoming. We practiced several calculations using moles. We then began a discussion of formulas; a formula is the ratio of moles of atoms in a substance (compound). We worked through some of the DCI, and the PowerPoint and then looked at question PS3.10 covering combustion analysis.
Class began with a conversation about chemical equation, in that they are a symbolic representation of a chemical reaction. Chemical equations contain formulas (along with phases) and coefficients to form a balanced chemical equations. IMPORTANT coefficients represent the ratio that reactants react and products form. So we next discussed the first clicker question which showed a particulate representation of a chemical reaction. The question asked for the balanced chemical equation. Several important points were made. Based on the question the ICE (Initial: Change: Ending) table was introduced as a way to organize all of the information shown in the particulate level diagrams. From the BCE discussion of chemical reactions, balancing equations and determining who the limiting reagent and excess reagent are in a reaction. The ICE table was introduced and how to use an ICE table to determine the amounts of products formed in a chemical reaction. We worked on an activity that we distributed in class.
We began with a clicker question covering chemical equations and then continued our discussion of ICE tables and stoichiometry by doing several problems.
We did a stoichiometry clicker questions and then introduced a solubility table and how to read it, and then discussed one example of a double replacement reaction. We wrote the equation in three forms; molecular, ionic and net ionic.
We discussed double replacement, neutralization reactions and single replacement reactions. We also disccued molecular, ionic and net ionic equations. At the end of class we started talking about Molarity (M) as a unit of concentration.
We did some molarity clicker questions to start the class. I had brought some volumetric flasks to class to demonstrate how to prepare solutions of different concentrations. I had also brought some solid copper(II) sulfate pentahydrate which I had pre-weighed using an analytical balance. I added the solid to the flask and then added about 50 ml of water and swirled the flask until all the copper(II) sulfate dissolved. Then I added enough water to reach the etch on the neck of the flask. The remainder of class we spent doing sample calculations of stoichiometry questions using molarity.
We began with a short discussion of the ACA and then started a PowerPoint to introduce Chapter 6 content on thermodynamics. We discussed some important terms and then we went over the BCE. After that we discussed the DCI (page 37) and went through all of the questions. Right at the end of class we invented the relationship between heat and mass of substance, its specific heat ('c') and the change in temperature of the substance. Mathematically the relationship is q (heat) = mass * c * T.
We continued our discussion of q = mass * specific heat * T discussing mixing hot and cold water, and the addition of hot metal to water. We also discussed the heat associated with adding a salt to water.
We discussed reactions in water and determining the heat produced or released. We also discussed bomb calorimeters.
We continued our discussion of calorimetry and did a number of different calculations to determine the heat released per mol of a substance, and then discussed enthalpy and formation reactions.
Thursday, October 15, 2015
No class
We Discussed the BCE and ACAand solved a problem using HEss' Law to determine the enthalpy of the combustion of 1 mol of ethane gas. We talked about the mathematical relationship that allows the use of standard heats of formation for compounds to determine the standard enthalpy of reaction. Near the end of class we began a discussion of the electron in the atom by considering the strange shape of the periodic table, and wondering why the table has the shape it has.
We discussed light and properties of waves: including wavelength, frequency and speed of light. We did several calculations using the releationship between wavelength, frquency and the speed of light. We also discussed the relationship between energy and frequency of light. Near the end of class we began an exploration into the arrangement of electrons in atoms. We discussed the relationship between the energy requeired to separate an electron from its nucleus in terms of the charge on the nucleus and the distance of the electron from the nucleus.
We Discussed the BCE and ACA
We completed our discussion of the arrangement of electrons in atoms with the invention of sublevels. We discussed the s, p, d, and f sublevels and how many electrons each can hold. With the knowledge that electrons occupy levels and sublevels we discussed the electron configuration of an element as a way to organize all of the electrons in atoms. We discussed how the shape of the periodic table revealed the four different sublevels. We looked at a simulation that showed the energy level diagram for a multi-electron atom so we could see the energies of all of the electrons.
We discussed
We spent much of class discussing the third exam. We went over Q4 in detail. We also discussed the 'curve' algorithm used to generate the exam score posted on the Grades Page. We briefly discussed ionization energies and started talking about trends.
We discussed periodic trends: ionization energy across periods, ionization down groups, and ionization energies within atoms. We discussion atomic and ionic radii and electron affinity. Near the end of class we started talking about ionic bonding and lattice energies.
We finished up a discussion of lattice energies and started talking about covalent bonding and Lewis Structures. We followed a series of steps to draw Lewis structures for moleculaes and polyatomic ions.
We discussed Lewis structures of simple compounds, and compounds with multiple bonds. We discussed resonance structures, and formal charge as a way to understand why certain, possible resonance structures, could be eliminated, or at least identified as less favorable. We also looked at the molecular structure of a compound and measured its bond angle. We also mentioned electronegativity as part of the process for determining the skeletal structure for a compound.
We discussed resonance and electron rich and electron deficient central atoms. We drew some additional Lewis structures. We look at chemical reactions and bond energies and discussed how to estimate the enthalpy of a reaction from bond energies. Bond energies are always endothermic, bur when a bond is formed the bond energy is energy released. We finished class talking about molecular geometries and shapes of molecules.
We discussed how PS12 is being scored followed by some discussion of the online activity due on Friday, December 4, 2015 by 4:00 pm in PS201. Also we discussed laboratory Check-out that occurs during pre-finals week. Next we discussed calculating the enthalpy of reaction using bond energies. Following bond energies we discussed VSEPR molecular geometires and bond angles. Of particular importance are the molecular geometries and bond angles for central atoms with two-, three- and four-domains of electrons. We also discussed the bond angles around central atoms with these molecular geometries, and why some bond angles are different from the ideal bond angles. For example in SO2 the O-S-O bond angle is less than 120°, not equal to 120° because the lone-pair/bonding-pair repulsions are greater compared to the bonding-pair/bonding-pair repulsions. Following the VSEPR discussion we talked about Valence Bond Theory. We discussed what atomic orbitals are involved in forming the covalent bond in H-H (H2), H-F, F2, and Cl2.
We discussed the BCE and ACA and continued our discussion of Valence Bond Theory. We discussed how the using atomic orbitals to describe the bonding in H2O, NH3 and CH4 did not agree with the bond angle data obtained from experimental evidence. So we covered a model where atomic orbital are mixed to form hydridized orbitals on oxygen, nitrogen and carbon. Checkout these lecture notes.
We discussed the Ideal Gas law. We derived the Ideal Gas Law (PV=nRT) from experimental data collected for the BCE. We discussed single value and change of condition types of problems. We also discussed how we could use the Ideal Gas law in stoichiometry type problems.
Class Video from Fall 2014
Click on the date below to view the lecture video. NOTE: It will take 30 seconds or so to load the video. If you are on a connection off campus, it may take longer. I recommend viewing the videos while you are on campus.
This was the first lecture of the semester and we discussed the structure of the course, grading, and the class web site.
In this lecture discuss matter in terms pure substances and mixtures. We discussed elements, compounds, atoms, molecules, mixtures in terms of particlate diagrams. We also discussed physical and chemical changes. Everyone was left with the task of having to draw a particulate diagram in the DCI activity.
We began by reviewing the ACA#2 for the class. In Q3 it was interesting that a majority of students felt the best equation to describe the chemical reaction was 4SO2 + 5O2 --> 4SO3 + 3O2. There were two errors in that logic. First O2 can not be both a reactant and a product, second coefficients do not represent how many of each particle are present. We also discussed the chemical equation for the reaction between Na(s) and Cl2(g). We then discussed parts of the BCE#2 and went through the PowerPoint for the lecture. The class has a good grasp of significant figures, but had difficulty reporting result of calculations to the correct number of significant figures.
We began by doing two clicker questions. One covered particulate level models of phase changes and the other question covered addition of numbers expressed in scientific notation. We then discussed ACA#3 Q2c. We then discussed conversion and tried a few conversion questions. Based on the ACA results over 75% of students can do the very straightforward conversion questions. So we discussed the more complex conversions. Students were having difficulty with density units. We ended lecture discussing the periodic table and referred to the atomic number and the atomic mass number that appears for each element.
We started with a clicker question on density conversion problem. Then we discussed atomic number, atomic mass and mass number. We discussed the units on the atomic mass and the definition of the atomic mass unit. We discussed isotopes and then developed the relative weighted average atomic mass for an element and did a calculation. We ended class discussing nomenclature of simple ionic compounds.
We began with a clicker question calculating the frational abundance for two isotopes of element Z. We discussed ACA#5 and #5 and reviewed some common errors in naming compounds or writing formulas that contain polyatomic ions. We also mentioned compounds that contained ammonium ions. We discussed synthesis and combustion reactions and how to predict products for those reactions and how to balance equations. Lots of good examples in Problem Set #3. Be sure to try the nomenclature DCI activities.
Class began with a discussion of the BCE for the day's class. We did several clicker questions. We discussed moles, molar mass, and Avogadro's number. We did several different types of questions using moles.
We began with a clicker question covering the first exam. The consensus was the exam was hard but there was enough time to complete the exam. More information about the exam will be forthcoming. We practiced several calculations using moles. We then began a discussion of formulas; a formula is the ratio of moles of atoms in a substance (compound). We worked through some of the DCI, and the PowerPoint and then looked at question PS3.10 covering combustion analysis.
Class began with a discussion of the BCE for the day's class. We began a discussion of chemical reactions, balancing equations and determining who the limiting reagent and excess reagent are in a reaction. The ICE table was introduced and how to use an ICE table to determine the amounts of products formed in a chemical reaction. We worked on an activity that we distributed in class.
We began with a discussion of the ACA for class and then continued using the ICE table for several different types of questions.
Class began with several clicker questions about predicting products for a synthesis and a combustion reaction. Then we inntroduced 4 more types of reactions; double replacement, neutralization, single replacement and decomposition reactions. Each was described in terms of the nature of the reactants. We looked at a video that modeled what happens when an ionic solid is dissolved in water. We practice writing products of double replacement reactions, then we wrote ionic and net ionic reactions.
We began with a discussion of the ACA for class a percentage of students were doing the ICE table incorrectly. We then moved to the BCE and discussed solubility and some common erros with identifying the formula (with charge) for the cations and anions for soluble substances. We then reviewed a sample double replacement reaction and wrote the molecular, ionic and net ionic equations. Then we discussed neutralization reactions. There are three types of these; strong acid and strong base neutralization reactions, weak acid and strong base neutralization reactions, and strong acid and weak base neutralization reactions. Then we discussed single replacement reactions; I discussed three examples of single replacement reactions. Then I introduced Molarity and showed how to prepare a solution (very important) and did some calculations.
Class began with several clicker questions about molarity. We also discussed several issues with the BCE. Then we discussed molarity in stoichiometry. Since ICE tables are completed in units of moles, we just need to remember that volume * (mol solute/volume) = moles. Be sure to check out the ACA for todays class for an excellent molarity problem.
We began with a short discussion of the ACA and then started a PowerPoint to introduce Chapter 6 content on thermodynamics. We discussed some important terms and then we went over the BCE. After that we discussed the DCI (page 37) and went through all of the questions. Right at the end of class we invented the relationship between heat and mass of substance, its specific heat ('c') and the change in temperature of the substance. Mathematically the relationship is q (heat) = mass * c * T.
We continued our discussion of q = mass * specific heat * T discussing mixing hot and cold water, and the addition of hot metal to water. We also discussed the heat associated with adding a salt to water.
Tuesday, October 14, 2014 We discussed reactions in water and determining the heat produced or released. We also discussed bomb calorimeters.
Thursday, October 16, 2014: No class
We discussed the heat associated with a chemical reaction and how to calculate qreaction knowing the heat absorbed by the solution and the calorimeter. Following that discussion we introduced enthalpy and the nature of a state function in terms of multiplying a reaction by a number, reversing the reaction, the phase of the reactant and products and Hess' Law.
We discussed enthalpy of formation and how Hess' Law can be used to determine the enthalpy of reaction for a larger number of reactions. Near the end of class we began a discussion of the atom.
Gelder went off on the equation M1V1 = M2V2, saying that you can not use that equation when calculating concentration of an acid or base, or the volume of a base require to neutralize an amount of acid. Have to use the balanced chemical equation to establish the stoichiometric ratio between the acid and base reacting. After that the discussion continued with a discussion of waves, and calculating wavelength, frequency and energy for a photon of light. Near the end of class we started an investigation of the structure of the atom and what the electron is 'doing'.
We looked at an activity the used ionization energy data to invent the concept that the electrons in an atom are organized into shells. We learned that there are 2 electrons in the first shell of an atom, 8 electrons in the second shell and 18 electrons in the third shell, etc. We also investigated photoelectron energy data to understand that electrons in a shell can be in different sublevels.
Discussed how photoelectron spectra can be used to invent the idea that electrons in a particular shell will occupy subshells. Data was presented to show that in the second shell the eight electrons distribute between two subshells. One subshell holds a maximum of two electrons, and the other subshell can hold six electrons. We discussed the property of spin for an electron. We also discussed the idea (no evidence was provided for this) that two electrons can occupy the same region of space as long as they have opposite spins. this is what we know as an orbital.
Discussed electron configurations for multi-electron atoms and ionization energy trends across periods, down groups and for an individual atom. We looked at an animation that depicted the energy-levels, sublevels and orbitals for atoms.
Lewis structures were introduced. We discussed the approach to drawing Lewis structures for simple compounds. 1) Count the valence electrons; 2) draw a skeletal structure (least electronegative element as the central atom, most electronegative element(s) are terminal; 3) distribute electrons to the terminal atoms so all have an octet; 4) remaining electrons placed on the central atom.
We looked at Lewis structures that required more than one resonance structure to complete represent the structure. We discussed formal charge and how it can be used to eliminate resonance structures from consideration.
In class we discussed the ACA from the previous class. We continued with our discussion of using bond energies to determine the enthalpy of a reaction. When breaking bonds, energy is required (endothermic), when bonds are formed energy is released (exothermic). The enthalpy of a reaction is result of these two components. Practiced doing a calculation. VSEPR was the next topic. Must be familiar with the different shapes possible and the bond angles of the atoms in the different shapes.
Continue with our discuss of VSEPR. The Molecular Structure activity that was done in laboratory is very important. We used Jmol to view the collection of sample molecules that you are responsible for. Those include compounds or ions containing central atoms with two, three, four, five or six domains of electrons. Students are responsible for the molecular geometry and the approximate bond angles of TA-CA-TA. The BCE introduced a discussion of how we use atomic orbitals on atoms sharing electrons to understand the bonding in simple compounds or ions. In class we discussed a new model that involves hybrid orbitals to better describe the molecular stucture of a particular set of compounds and ions.
We started the discussion talking about polar bonds,nonpolar bonds and polar and nonpolar molecules. With the exception of bonds in elements, bonds in compounds are polar. However, whether the molecule is polar or nonolar depends on the molecular geometry. We discussed 'rules' forpredicting polarity. Next we completed our discussion on hybrid orbitals. We discussed sp3, sp2 and sp hybrid orbitals and we discussed how to identify the atomic orbitals or hybrid orbitals that are involved in forming a covalent bond.
Focused on gas laws in this class. We discussed single-valued problems, change of condition problems, using stoichiometry and gas laws and interpreting the Kinetic Molecular theory of gases.
Class Video from Fall 2013
Click on the date below to view the lecture video. NOTE: It will take 30 seconds or so to load the video. If you are on a connection off campus, it may take longer. I recommend viewing the videos while you are on campus.
This was the first lecture of the semester and we discussed the structure of the course, grading, and the class web site.
In this lecture discuss matter in terms pure substances and mixtures. We discussed elements, compounds, atoms, molecules, mixtures in terms of particlate diagrams, and by looking at some videos of reactions.
We began by reviewing the ACA#2 for the class. In Q3 it was interesting that a majority of students felt the best equation to describe the chemical reaction was 4SO2 + 5O2 --> 4SO3 + 3O2. There were two errors in that logic. First O2 can not be both a reactant and a product, second coefficients do not represent how many of each particle are present. We also discussed the chemical equation for the reaction between Na(s) and Cl2(g). We then discussed parts of the BCE#2 and went through the PowerPoint for the lecture. The class has a good grasp of significant figures, but had difficulty reporting result of calculations to the correct number of significant figures.
We began by doing two clicker questions. One covered particulate level models of phase changes and the other question covered addition of numbers expressed in scientific notation. We then discussed ACA#3 Q2c. We then discussed conversion and tried a few conversion questions. Based on the ACA results over 75% of students can do the very straightforward conversion questions. So we discussed the more complex conversions. Students were having difficulty with density units. We ended lecture discussing the periodic table and referred to the atomic number and the atomic mass number that appears for each element.
We discussed ACA#4 and #5 and BCE#4 and #5. We discussed another, more challenging, RWAAM problem where we determined the fractional abundance of two isotopes given the isotopic masses of each isotope and the elements Relative weighted average atomic mass. We discussed nomenclature of simple ionic and covalent compounds.
We began with a clicker question calculating the frational abundance for two isotopes of galium. We discussed ACA#6 and #6 and reviewed some common errors in naming compounds or writing formulas that contain polyatomic ions. We also mentioned compounds that contained ammonium ions. We discussed synthesis and combustion reactions and how to predict products for those reactions and how to balance equations. Lots of good examples in Problem Set #3. Be sure to try the nomenclature DCI activities.
Class began with a discussion of the BCE for the day's class. In today's class Lisa discussed moles and did several examples of how moles can be used in different calculations. Be sure to do ACA#8 before the exam on Wednesday, September 11th at 5:30 pm.
We began with a clicker question covering the first exam. The consensus was the exam was hardbut there was enough time to complete the exam. More information about the exam will be forthcoming. The three students with the highest exam scores were recognized. We then began a discussion of formulas; a formula is the ratio of moles of atoms in a substance (compound). We worked through some of the DCI, and the PowerPoint and then looked at question3.122 in our textbook covering combustion analysis. Additional time was given to complete PS#3, and a HELP Session was announced for Friday, September 13th at 4:40 pm.
Class began with a discussion of the BCE for the day's class. We began a discussion of chemical reactions, balancing equations and determining who the limiting reagent and excess reagent are in a reaction. The ICE table was introduced and how to use an ICE table to determine the amounts of products formed in a chemical reaction. We worked on an activity that we distributed in class.
We began with a discussion of the ACA for class and then continued using the ICE table for several different types of questions. A HELP Session was announced for Monday, September 23rd at 5:00 pm in PS153.
Class began with several clicker questions about predicting products for a synthesis and a combustion reaction. Then we inntroduced 4 more types of reactions; double replacement, neutralization, single replacement and decomposition reactions. Each was described in terms of the nature of the reactants. We looked at a video that modeled what happens when an ionic solid is dissolved in water. We practice writing products of double replacement reactions, then we wrote ionic and net ionic reactions.
We began with a discussion of the ACA for class a percentage of students were doing the ICE table incorrectly. We then moved to the BCE and discussed solubility and some common erros with identifying the formula (with charge) for the cations and anions for soluble substances. We then reviewed a sample double replacement reaction and wrote the molecular, ionic and net ionic equations. Then we discussed neutralization reactions. There are three types of these; strong acid and strong base neutralization reactions, weak acid and strong base neutralization reactions, and strong acid and weak base neutralization reactions. Then we discussed single replacement reactions; I discussed three examples of single replacement reactions. Then I introduced Molarity and showed how to prepare a solution (very important) and did some calculations.
Class began with several clicker questions about molarity. We also discussed several issues with the BCE. THen we discussed molarity in stoichiometry. Since ICE tables are completed in units of moles, we just need to remember that volume * (mol solute/volume) = moles. Be sure to check out the ACA for todays class for an excellent molarity problem.
We began with a short discussion of the ACA and then started a PowerPoint to introduce Chapter 6 content on thermodynamics. We discussed some important terms and then we went over the BCE. After that we discussed the DCI (page 37) and went through all of the questions. Right at the end of class we invented the relationship between heat and mass of substance, its specific heat ('c') and the change in temperature of the substance. Mathematically the relationship is q (heat) = mass * c * T.
We discussed the OSU calorimeter and how to determine the heat released in a chemical reaction.
We continued our discussion of calorimeter discussing heat capacity of calorimeters and how a bomb calorimeter works. We did several sample calorimetry problems.
We discussed the heat associated with a chemical reaction and how to calculate qreaction knowing the heat absorbed by the solution and the calorimeter. Following that discussion we introduced enthalpy and the nature of a state function in terms of multiplying a reaction by a number, reversing the reaction, the phase of the reactant and products and Hess' Law.
Thursday, October 17, 2013
No class.
We discussed enthalpy of formation and how Hess' Law can be used to determine the enthalpy of reaction for a lareger number of reactions. e several examples.
We began discussing waves and their importance in understanding the structure of atoms. We discussed wavelength, frequency, the speed of light an the relationship between energy and frequency of light. We began discussing an activity that uses Coulombs law to understand the nature of the interaction between the positively charged nucleus and the electron.
We discussed an activity which used ionization energy data for elements in the first three periods to develop the concept of shells of electrons in atoms.
We began continued our discussion of the electronic structure of the atom. We reviewed the evidence for the existence of shells that electrons occupy. We discuss the energy level (shell) diagram and how to interpret the diagram. We the discussed low resolution photoelectron spectroscopy data and how that provides evidence for the there being different kinds of electrons in each shell. We end class with a brief discussion of electron configuration.
We discussed the ACA and BCE briefly and then discussed electron configuration in more detail.We discussed valence electrons and inner core electrons and we looked at a simulation of an energy level and an orbital diagram. We discussed orbitals and electron spin. We briefly reviewed ionization energy.
We began continued our discussion of the electronic structure of the atom. We completed our discussion using the energy level (and orbital) animation. We discussed how to write electron configurations for ions. We discussed trends in ionization energy and how to explain those trends. We also mentioned atomic radius, the trends and explanations.
We discussed the ACA and BCE briefly and then discussed began a discussion of ionic and covalent bonding. Lattice energy, as a measure of the strength of an ionic bond, was discussed. We looked at L.E. data and discussed the pattern that was present. L.E. is directly proportional to charge on the ions and inversely proportional to the distance between ions. We ended class drawing Lewis structures of atoms.
We discussed the ACA and BCE briefly and continued our discussion on Lewis structures. We worked on the activitiy in the DCI workbook on pages 65 and 66. We learned about the steps to successfully drawing Lewis structures for compounds. Electronegativity was introduced and discussed in the context of selecting the central and terminal atoms in a Lewis structure.
We discussed the ACA and BCE briefly and then continued discussing Lewis Structures for covalent compounds and polyatomic ions. We began discussing CO2 because the Lewis structure introduces multiple bonding. We also discussed formal charge as a way to help decide which possible Lewis structures are good and which are not as good. Next we discussed O3 as it introduces resonance structures. We covered bond order. We also discussed H2SO4 as an example of a compound with a Lewis structure that has formal charges that are not zero, yet the Lewis structure obeyed the octet rule. We then changed the Lewis structure to reduce the formal charge. We did several additional Lewis structure with central atoms that were electron deficient and electron rich.
We discussed the ACA and BCE briefly and briefly reviewed Lewis structures. Covalent bond energies was the next topic. When breaking bonds, energy is required (endothermic), when bonds are formed energy is released (exothermic). The enthalpy of a reaction is result of these two components. Practiced doing a calculation. VSEPR was the next topic. Must be familiar with the different shapes possible and the bond angles of the atoms in the different shapes.
We discussed the ACA and BCE briefly and then continued discussing Lewis Structures for covalent compounds and polyatomic ions. We discuss the atomic orbitals that are involved in formiing the covalent bond in HF, H2O and NH3. We discussed how using atomic orbitals on oxygen and nitrogen central atoms in H2O and NH3 lead to different bond angles compared to observed bond angles. Then we considered a central carbon atom and considered how, using atomic orbitals, carbon could form four bonds. SO we introduced a new model for orbitals on central atoms that did a better job at explaining the observed bond angles. Hybridizing a 2s and three 2p atomic orbitals produced four sp3 hybrid orbitals. Mixing a 2s and two 2p atomic orbitals produce three sp2 hybrid orbitals. Mixing a 2s and a 2p atomic orbital produce two sp hybrid orbitals. We looked at the bond angles produced by these hybrid orbitals.
We discussed the ACA and BCE briefly and then began discussing gases and their behavior. We discussed the relationship between the variables: pressure, volume, temperature and moles. We did sveral types of problems using the ideal gas equation, and how to use the ideal gas law in stoichiometry problems.