This trimester  in AP Chemistry thus far we have been covering the topic of Thermodynamics. This topic covers both enthalpy and entropy as well as a few other concepts. We spent lots of time in class doing worksheets and using our famous white boarding technique. This technique has been very beneficial for myself and many other classmates all year as it allows us to see our other peers' thoughts and ideas and use them to learn more. We also spent a little bit of time doing a quick mini-lab that involved precipitates and net ionic reactions.

            In our introduction to Thermdynamics we discussed the difference between heat and temperature. From our discussion we concluded that heat is a measurement of the total energy that is present in the system while temperature is the measurement of the heat content of the system. In our introductory discussion, we also figured out that heat is due to the breaking or making of bonds. Temperature is also related to the transfer of heat. Lastly we learned that when heat leaves the system and goes to the surroundings it is considered an exothermic process and when heat goes into the system from the surroundings it is considered an endothermic process. All in all, to reflect on this concept, I thought it was quite simple to comprehend, although this would not really be the case for topics to come. Learning and understanding the differences between heat and temperature was fairly simple for me.

            Next we moved onto calorimetry. Here we continued to work on distinguishing between endothermic and exothermic processes. We worked on some worksheets using the formulas that we learned for the change in heat. Change in heat is equal to the mass multiplied by the specific heat capacity and the change in temperature. Calorimetry is useful to us because from this method we can find the energy change in the system by finding the energy change in the surroundings, and this can be very important. We also talked about the enthalpy of fusion and the enthalpy of vaporization. Enthalpy of fusion has to do with the process of melting and the breaking of bonds. When vaporization occurs the rest of the bonds are broken. To reflect on calorimetry, this began to really test me, and I was having quite a bit of trouble with it. After spending more time learning about calorimetry and vaporization, I began to comprehend it a little more, although I still definitely need more work before the exam.

            In our last topic we discussed entropy. Entropy can be defined as the possible number of microstates that are available to the system. It is represented as delta S in the equation. Entropy is greater than zero when melting or vaporizing takes place. It also occurs when the number of moles increases. Entropy can be calculated as the sum of the products minus the sum of the reactants. The last thing that involved entropy was Gibbs free energy law. This was used to figure out whether or not a process is thermodynamically favored. We also dived a little bit into standard state conditions and things of that nature. To reflect on these topics, I also thought they were very difficult at first. I had some trouble understanding how to apply the formulas and equations and solving. I also need more work on the topics of entropy and Gibbs free energy law before the exam.

            These were all of the main ideas that we covered this week. Basically they all go hand in hand with each other as they all fall under the larger scope of thermodynamics. Most of this unit had to do with math and I found that to be much easier and more helpful to my understanding of the topics. Equations and numbers make some of the concepts easier to understand because you are using set equations and concrete things. With the equations visible to me and understanding each of the factors in the equation, I can fully understand and comprehend what is going on in the process of each reaction. I would say I definitely participated in class rather well as I spent much time struggling with worksheets and whiteboards and discussing thermodynamics with my table as well as participating in class discussions. I would rate my understanding of the material at this point of time at 6/10.

Gibbs free energy equation

       This was not too difficult a week in AP chem, in terms of how much we did. I do not understand many of the topics thoroughly though, and I am quite nervous for this upcoming test on tuesday. The quizports helped a little but I still need more work which is a problem because I do not have any time on Monday. I hope I am able to study during class and during other hours in school so that I do well on this test.
   
        On Monday, we went over the white boards we made as table groups, as a class. We made these white boards on IMFs and all molecular bonding and what is related to it or depends on it. Some of these white boards contained a LOT of good information. These white boards talked about almost all aspects of IMFs and what they are, where they're located, and how strong they are. The other whiteboards didn't contain much, maybe a drawing or two that nobody besides them could understand. My white board was moderate. I believe we covered most of the subjects of discussion, but not all the small details that may be more necessary than they seem. I believe my table understands the material fairly well. To reflect on this whiteboarding, it was not too difficult of material and I understand most of it. Whiteboarding definitely helps me get things down.

         On Tuesday, we had no school. On Wednesday and Thursday, we worked on the work sheet named "AP WORKSHEET 02f: Bonding and Properties" and the packet named "Ionic Bonding, Metallic Bonding, and Intermolecular Forces". I am still working on mastering the differences between all the different types of bonding. After doing the Hot Pots and Task Chains, I feel as though it really helped me with understanding and memorizing all the things I need to understand and know for the test, which is really helpful. To reflect on the worksheet and packet I thought they were quite difficult. It is hard for me to know which intermolecular forces are involved when and what roles they play in boiling and melting points along with other things.

        On Friday, we did a mini lab sort of activity. I was partners with Julien and Yishai, as always, and we kind of joined up with Sarika's group. We decided to work on Part 2 first. Part 2 was the longer of the two parts, and we decided to do this first in case we ran out of time, so we could quickly and easily do the other part if need be. In Part 2, we used unknown substances. We had to determine the identity of the six unknowns, and we had a table of six possibilities. We drew the Lewis structures, and began putting the unknowns on the slides and the table. We quickly figured out which one was water, and which was glycerin. The other ones all had very low surface tension, and that was a characteristic of Acetone, Nonane, and Ethanol. I was able to figure out which was Acetone by wafting. I know the smell of acetone, because it is in nail polish remover. I used my sense of smell for the ethanol as well. What was left was the nonane. We also checked to see which ones dissolved into water easily. In the second part of part 2, we swirled these substances around, and we checked to see how viscous each was. The observations matched the ones we had from the first part of part 2. To reflect on this lab, I like working with other people in the class and it was pretty fun overall.

        In Part 1 of the activity on Friday, we tested whether or not substances conducted electricity. My group's predictions were a little off for the "In Aqueous Soln" column. I, for one, thought that they'd all be conductors, since water was a conductor. I found out only Sodium Chloride is a conductor when dissolved in water, out of these seven substances. I also found out that my whole center column was incorrect, besides Sodium Chloride. This activity helped me to understand that ionic solids are not good at conducting electricity AT ALL.

                                                                          
                                                                        Lattice Energy

 This week in chem, we began mastering our knowledge of IMFs, or intermolecular forces. We went more in depth into Van der waals forces, such as Hydrogen bonds, dipole-dipole, induced dipole, and London Dispersion Forces, or LDFs. We also touched on dipole-ionic bonds, and the forces between metals, which are not Van der waals forces. We began the week working on a POGIL on Intermolecular forces, or foced between molecules, in liquids and gasses. This was a bit tough to do, but after the reading you gave to us, it became easier and easier the more we read at my table. That night I also watched some lectures on it, and the POGIL started to become completely clear to me. I was able to finish it with ease after reading the packet and taking notes on these forces. Since we did a lot of practice on these things, it is now sticking in my mind, and I won't forget it for the test. To reflect on this, it was helpful in allowing me to fully be able to understand and memorize everything about intermolecular forces, this is helpful because I will definitely need it for the test.

        Later, in our table groups, we started on a "water" POGIL. This POGIL was fun especially the magnet part. My table didn't have any trouble in this POGIL, besides a few disagreements here and there which were solved by explanation. This POGIL helped me and my table understand Hydrogen bonds, induced dipoles, and sizes of different atoms in a molecule like NaCl, or sodium chloride. I think we could possibly use more of an explanation on this, but we get the gist of it. To reflect on this pogil, I could definitely use more work on the topics covered. I hope we will do more things with hydrogen bonding, induced dipoles, and the sizes of different atoms in a molecule.

         Putting our answers on the board for the Lecture 23 Intermolecular force worksheet really helped my table. Most groups got the answers right, just not the explanations. We were one of those groups. The wrong explanations helped, because you were then able to explain exactly what everyone did not understand, and change our answers so we would remember what we did wrong. Some people got the explanations right, and they were able to explain how they got those answers. To reflect on this, whiteboarding definitely helped me understand the concepts we've learned a little better. My favorite part was when we were asked to summarize all the things we'd learned this unit on the whiteboard. this helped me remember things that we'd learned earlier and know the basics of them. Whiteboarding really helps me learn things by listening to my classmates' explanations.

         The homework this week was not a huge amount, which I really enjoyed. I was able to study more for this class as well as others. To reflect on this week in AP chemistry, we learned quite a few new concepts regarding the intermolecular forces. These concepts were not exactly 'hard' but they were difficult to grasp at first, but doing more work with the things we've learned has helped me understand them further.

    This week was another full and busy week of AP chem. We took a big test on Lewis structures and then worked for the rest of the week on ionic bonding. A little side note: our class took an actual AP Chemistry multiple choice exam and this was a very difficult test for all of my class.

            The first half of this week we spent on reviewing for testing and actual testing. We spent Monday on reviewing Lewis structures, polarity, hybridization, and VSEPR Theory. All of this led up to a huge test the following day. The test was a very comprehensive one and was a good challenge. I found the test to require quite a bit of knowledge on the materials that we learned but I felt pretty confident taking it. On Wednesday we took an AP Chemistry multiple choice exam which was pretty difficult. It was definitely quite difficult for me as a I only got 13 questions out of 60 right. To reflect on this, it made me very nervous for the ap exam. I hope at the end of the year I am able to easily do well on this multiple choice exam.

            The last two days of this week we spent on doing a couple intro lessons to ionic bonding and metals. The basis for an ionic bond is a bonding between a cation and an anion. We can see that the formula will always have to be a balance between the negative and positive charges of two atoms. Ionic compounds will always be made up of a metal and nonmetal. Unlike covalent bonds, there is no sharing of electrons in ionic bonds. However, there is a strong attraction between the two ions due to the Coulombic force. Usually in an ionic compound there will be a negative charge on the metal and a positive charge on the nonmetal. The charges are generally determined by the group that the element is found in with exceptions for the transition metals. To reflect on this topic I thought it was very simple, it was a little hard to follow along at times during this lesson but I understood basically everything.

            We also learned about some properties of ionic bonds. We discovered that melting point can also be a representation of how strong the bond between the two atoms is. The higher the melting point, the stronger the bonds will be between the two atoms of an ionic bond. On Friday we spent a little bit of time on metals too. We learned about some of their properties and what alloys are. Alloys can be defined as a solution that has the properties and characteristics of a metal. To reflect on our work with metals I thought it was quite easy, although the concepts are likely to get much more complicated throughout the course of this unit.

            That's basically what we did this week. To reflect I thought it was a difficult week because I was very busy with soccer every single day. This made it very hard to find time to review for the test, although I felt very confident about it. I was extremely surprised that I didn't do better on the test and I really wish the tests were passed back in class so I can see my mistakes. Other than that I thought it was a good week of AP chem, my understanding of the new material was about a 9, and I participated in class activities well every day.

Example of an alloy

This week we had a lot going on in class. We did many different activities to help us better our understanding of the VSEPR theory and how molecular and electron domain geometries work.

            For the first half of this week, we worked online building our models that we had already learned about from our balloon and gum drop lab. We created a molecular orbital to represent our molecule and we could use this orbital to find out a lot of information. We looked at the dipole moments that occurred in the molecule and the individual dipole bonds that were present. From this we could see the partial charges in atom and could even better understand the partial charges in the molecule by looking at the electrostatic potential map. Atoms in the molecule that were the most electronegative appeared red on the map and the atoms that were least electronegative appeared as a cool color, either blue or green. We could also see the bond angles that were present in the geometries even though we already knew this from the worksheets and lectures that we had done previously.

            We found out from this lab that the unpaired electrons on the central atom are electron clouds that push down on the bonds of the molecule and reduce their angles and this is why they sometimes deviate away from their standard value.

            We also talked a little bit about pi and sigma bonds this week. Pi bonds occur when there is an overlap of the p orbitals while sigma bonds occur when there is an overlap of the s orbitals or sp orbitals. This concept was a little complex at first to understand but made more sense to me when I understood that sigma bonds occur in all bonds while pi bonds occur in bond orders that are higher than one (i.e.: a double or triple bond). For a double bond there is one pi bond and one sigma bond while for a triple bond there are two pi bonds and one sigma bond.

          The last thing we talked about this week is hybridization. This has to do with the amount of bonds and unshared pairs of electrons around the central atom in a lewis structure. For example if there are 2 bonds the hybridization is sp, if there are 3 it is sp2, and so on. Eventually you need to start using the d orbital. To reflect on this topic I thought it was quite easy and simple to understand, all you have to do is be able to count.

          To reflect on the entire week I thought I had a very good understanding and I participated well. At first I didnt really understand much of what was going on with bonding. This weekend I really spent an extremely long time working on chemistry and doing the quizzes online and now I feel extremely comfortable with the material. I now feel like I am a 9 on a scale of understanding the material. I am very happy because I was extremely anxious last week that I would not do well on this test, but now I am very comfortable with the stuff we've learned.

Here is a twenty minute video further explaining VSEPR theory: http://www.youtube.com/watch?v=nxebQZUVvTg

This week in AP Chem we worked a ton more on Lewis structures. We specifically zoned in on expanded octets in Lewis structures and also which Lewis structures is more correct. We spent some time with pogils and also did some practice problems to further our knowledge. To reflect on these pogils, I thought they were very helpful in allowing me to understand topics that were very confusing at times.

            Up to this point, we knew that there was a certain checklist needed for making Lewis structures. First, you must determine, from the compound, which atom is the least electronegative and place this atom as the center atom. This first step is extremely important and must be done correctly or else your lewis structure will be wrong. You choose the least electronegative atom as your center atom because you want this atom to be the least likely to take away electrons from atoms and be the most likely to share electrons with other atoms. Next, you must create bonds with the pairs from the outside electrons and the inside atom and complete the octets for each atom. ( Hydrogen has a complete octet with two electrons.) We then want to place any remaining unpaired electrons around the inside atom. This checklist is important because drawing a correct lewis structure is the basis for more complicated problems.

            This week we spent time going over what we learned on formal charges in a lecture last week. Formal charges can be defined as the number of valence electrons an atom as minus the bonds it has attached to it minus the number of unbonded electron pairs surrounding the atom. With the pogil we did we were able to determine that the most correct Lewis structure is the one that has the least formal charges, preferably a overall formal charge of zero on the compound. We learned that for certain atoms like oxygen you can have the formal charges memorized. If there is only bond attached to oxygen, it has a formal charge of -1. If there are two bonds attached to oxygen there is a formal charge of 0. If there are three bonds attached to oxygen, there is a formal charge of +1. There are many other atoms like oxygen which we need to have their formal charges based on number of bonds attached to them memorized. To reflect on our review of formal structures, I thought the pogil was very helpful. Formal charges are rather easy for me but sometimes it can be difficult to determine the most correct lewis structure based on the formal charge.

            We also completed another pogil regarding expanded octets. We learned that elements in the third period or lower can have extra pairs of electrons placed around them that can be more than a complete octet. This is because elements in the third period or lower have access to the d-orbital. To reflect on this pogil, it was kind of a difficult difficult concept to understand, but I think in the end after completing the pogil and asking a lot of questions I have it down pretty well.

             To reflect on this entire week in AP chemistry, it was a tough week filled with new and complicated concepts, but for the most part I understood everything. I do not really have any new questions about this week and I feel that I participated very well with my table and in class. I definitely still need to work more on how to draw lewis structures correctly before the upcoming test.

 This week was a lab week in AP Chemistry. We finished our data collection part of the lab on finding the mass of copper in a brass solution. We also worked on a few pogils to extend our knowledge about Lewis structures. We completed a pogil that had to do with bond order and bond strength, another one regarding  resonance and a third one on VSEPR theory. We learned an extensive amount of new ideas and concepts from these pogils that will likely be very important to us as the unit went on. To reflect on these pogils, I thought they were very helpful in allowing me to grasp new and difficult ideas.

            The first pogil we worked on was one that had to do with two main ideas, bond order and bond strength. Bond order occurs when you require many bonds to connect two atoms’ valence electrons together so that they are able to share electrons. A higher bond order will mean that more energy is needed to take apart this bond. A lower bond order means that it will take less energy to take apart the bond. We were able to understand this from working on the pogil on bond orders. To reflect on this pogil, I think it was quite helpful in helping us learn about bond order and bond strength. These are two important ideas that we will probably be using later in the trimester.

            In our next pogil we took a look at resonance in Lewis structures. We had already learned what those were about from the lecture quiz that we worked on last week. Resonance is when you can multiple Lewis structures from the bonding of the same atoms based on using different bond orders on different atoms. Another very important main concept that we learned from this pogil is that as bond order increases, bond length decreases. To reflect on this pogil, it was also very helpful and allowed me to understand the basic principles of resonance in Lewis structures 

            In the last pogil we did for this week, we worked on VSEPR theory. This theory shows us the overall shapes of molecules. We finished this pogil by creating a Lewis structure for an atom and then building a balloon model of that atom using the surrounding atoms and unbonded electron pairs as balloons. The central atom was in the center and not needed to be represented by balloons. This pogil helped show us what a compound will truly look like when it is bonded. To reflect on this pogil, I found VSEPR theory to be quite hard and complicated, but the pogil helped me a lot.

Diagram showing the VSEPR theory

           This week we also took part in a lab. We completed our data collection part of the lab. Our question which we are testing is what is the relationship between absorbance and concentration of Cu in a brass solution. Although I was not in class for the first day of the lab, I came back the second day and got down the data and had the lab described to me by one of my partners. We tested the relationship between absorbance and concentration by breaking down a brass screw in nitric acid to get it down to only Cu. We then took our absorbency data and will spend next week analyzing this data. To reflect on this lab, I thought it was pretty interesting and fun, I'm excited to do the lab report.

            I thought I had an alright grasp of the material that we worked with this week. I didn’t find it too complicated, but some of the ideas were difficult to understand, and i am still foggy on some topics. My participation in all of our work was 100% besides the day I was not in class. I don’t have any questions about anything we went over this week and I have seen that I still need to work on getting better at preparing for labs better, by coming up with better beginning questions.

          This previous week was not very eventful in AP Chemistry. We spent the first half of the week reviewing for our big exam on stoichiometry which covered limiting reactants, empirical formulas, and percent yield. To reflect on our review in class, I thought it was extremely helpful in preparing me for the test. The moodle quizzes online really helped me learn material which I had not quite understood before, as well as help me get more practice with harder problems like the ones we would see on the exam. Redoing these quizzes several times allowed me to see more and more problems, which ended up being extremely helpful, as the problems on the moodle quizzes were very similar to the ones on the stoichiometry exam. To reflect on the actual exam itself, I thought it was a very good challenge, and although I did fairly well, I feel like I could have done much better if I had more time to study. There weren't any problems that I had never seen before in one way or another, and I was pretty confident about how I did. The only thing I need much more work on is learning how to use significant figures better. This definitely caused me to lose some points on the free response exam, which I cannot have happen, because this doesn't reflect my knowledge on stoichiometry, but rather on how to round numbers.
          After taking the test we began working with Lewis structures. To reflect on this topic, I thought the lewis structure pogil was comprehensible and fairly simple, although there was some stuff I did not quite understand. The main ideas we covered regarding lewis structures were how to figure out which atom is the central atom and how to form the covalent bonds. To determine which atom is the central atom, you must figure our the electronegativities of the atoms. Then, you find out which atom has the lowest electronegativity and place it in the center. Then you form covalent bonds with unpaired electrons from the outside atoms to the inside atoms. Although we didn't really go over these in class, resonance and bond order were discussed in the lectures. I found these to be quite confusing and I hope we work on them more in class because I didn't really understand these concepts. Overall I found the lectures online this week to be kind of challenging, and I hope we work more with them in class.

          
          Overall, this week was not very eventful so there is not much to discuss.  I found the activities that we did to begin gaining knowledge on Lewis structures pretty straightforward and the lectures on resonance and bonding orders a bit harder and more complicated. I realized from taking the test this week that I need to work harder on doing more practice problems especially involving  and studying harder to get a higher grade on the test. I would still rate my understanding on the past material covered on the test and the new material that we learned this week at about a 4 out of 5. I was able to participate fully in all of the activities we did this week and that helped me broaden my thinking about Lewis structures and how they really work.
http://www.youtube.com/watch?v=8JsK6rPpi70  - This is a good video that further helped me learn to draw lewis structures.

          This week we expanded greatly on stoichiometry. We moved on from basic stoichiometry problems into problems involving limiting reactants and yield. We also learned about empirical formulas and molecular formulas. As we deepen our knowledge regarding stoichiometry, the more the the concept build on each other. For example, the concepts we used to do basic stoichiometry problems at the beginning of the year have been crucial in helping us solve problems involving more complicated ideas such as yield, limiting reactanta, and empirical as well as molecular formulas.
          We dove into limiting reactants through a Pogil which we completed in class. I found this pogil to be very helpful because it explained limiting reactants in chemistry through examples that are unrelated to chemistry which helped me get a grasp on the topic. From there, we did worksheets which gave us practice solving problems involving limiting reactants. To find the limiting reactant you must find out which of the reactants produces the lesser amount of the product. To figure this out we used our knowledge and experience with mole ratios and molar mass to perform calculations. I found these problems to be very simple and straightforward.
          Next we moved on to more complicated but still fairly simple stoichiometry problems which required us to find percent yield. We used lectures and worksheets to help us understand the concepts involved in finding the percent yield. To solve yield problems you must: balance the equation, determine the limiting reactant, determine theoretical yield, divide actual yield by theoretical yield, multiply by 100%. The process of solving thee problems is fairly simple, largely because it does not involve any complicated calculations.
          The last thing we worked on this week was determining empirical formulas. Similarly to limiting reactants, we learned about empirical formulas through a pogil. At first the concept of empirical formulas was very challenging to me but once we did the pogil and worksheets it became more clear. An empirical formula is a formula which represents the simplest ratio among the elements of a compound, however formulas with the same base formula do exist. The next concept we tackled was finding molecular formulas by dividing the molar mass by the empirical molar mass. I found this concept pretty easy and simple to understand. We also worked a tiny bit on particle diagrams which I found to be extremely confusing, and this is something I definitely need more work on, I hope we tackle these a bit more in class next week before the test.

Overall, I thought this week I was able to understand most of the concepts we covered very well. Like I said, the thing I am having some problems with at this point are particle diagrams, these are very confusing for me and I need some more work on them. On a scale of 1-5, I would say I am a bout a 4 on my level of comprehension of the ideas in AP Chemistry this week.

          This previous week our class did a lab lab which examined the relationship between the molar concentration of a solution and absorbency. Furthermore we also studied molarity and worked with a couple of stoichiometry problems. These were the main areas we covered in class and on the Moodle this week and they are interconnected. We learned that concentration is directly related to molarity and we used this information to aid us in our lab.
          The first activity we worked on this week was a lecture quiz online regarding molarity. The major and most important thing we learned from this quiz is the equation, Molarity (M) = moles of solute / volume of the solution in liters. This concept is critical to understand and is closely related to the idea of dilution we studied in the lab. Another important concept we learned from the lecture quiz is the fact that volume is temperature dependent. The first concept is related to the lab because in the lab we saw that the moles of solute (the blue dye) would decrease as we increased the amount of water in the solution and as the solution became more diluted. The temperature concept in the moodle   quiz is also related because it has to do with molarity and when the temperature goes up the volume goes up and the molarity will then decrease. Another thing we learned is about the different types of pipettes, their uses, and how they affect the amount of moles of a solution and the volume of a solution depending on which pipette you're using.

<-- We used a pipette like this in our lab to help accurately create the solutions.

<-- We used a cuvette to put the solution in and we put the cuvette in the colorimeter








          After doing the lecture quiz, we worked on  some difficult stoich problems. To do these we used the knowledge we previously had on molar mass, moles, and the relationship between grams and moles. Knowing this we were able to solve a lot of problems involving these concepts. An important equation for this secion was mass x molar mass = weight. by using this equation we were able to examine the relationship between moles, mass, weight, and atoms in the problems we did. Because the stoich problems were challenging for me, I looked for some extra help online and found the URL to a good video further explaining stoichiometry. http://www.youtube.com/watch?v=lVT0S-W_wEM
          The last thing we did this week was a lab examining the relationship between concentration and absorbency. To do this lab we first altered the concentration of many different solutions of blue #1 dye and water and finding the absorbency of the different solutions. Then we looked at different absorbency levels of Powerade and Gatorade G2 to find the concentration of blue #1 dye in these solutions. We then developed a linear equation between between these two variables and performed calculations with this knowledge. This lab required previous information from the lecture quiz and stoich problems.
          We came to figure out and understand these problems through experimentation and completing many problems in class. The thing that confused me the most this week was Beers law, especially since there was a problem we did in class on Friday that required us to apply Beers law. I would definitely like to gain a better understanding of the relationship.I participated very well this week, especially in the lab which I found to be very fun and interesting. Overall, on a scale of 1-5 I understand the material covered this week at about a 3. At this point I do not have any new questions to ask, but I need to review more so I can better understand everything.