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.