SG Chem - Seventh Post

This week in chem 2 we learned the rules to naming ionic and molecular compounds in preparation for the upcoming test. On Monday we were given a packet of paper that gave us the charges for selected elements on the periodic table. We then had to use that information to make observations about certain charges and then solve problems that were given to us.

Periodic table with selected element charges 

We realized that all the elements in column one, or the column closest to the left, have a positive charge of one. If you move one to the right you'll see all the elements have a positive two charge, increasing by one. This is similar to the columns on the very right, where all the elements have a  charge of negative one and when you move one column inward you'll see that each element has a charge of negative two, increasing by a charge of negative one. We made simple observations like this to help us understand and remember which elements had which type of charge. This sheet taught us that to write the formula for the given ionic compound we needed the charges of both elements to balance out to zero. 

Once we got an understanding of what the charges for single elements were we started learning about polyatomic ions, these are ions with multiple elements that create one type of charge. For example, nitrate is a polyatomic ion that consists of one nitrogen and three oxygen. Although there are two elements, oxygen (with a charge of negative two) and nitrogen (with a charge of negative 3) they are bonded together giving the entire ion (NO3) a charge of negative one. Another thing that is important to mention is that poly-atomic ions only consist of multiple non-metals, poly-atomic ions do not contain metals. 

Up to this day we only had learned about elements and compound containing metals, but on Thursday we were introduced to compounds that do not include metals, these are called molecular ions. When this happens you use prefixes such as mono, di, tri, etc. to tell how many atoms of each element there are. For example for ClF5 would be named Chlorine pentafluoride because there is one chlorine atom and five fluoride's. Because fluorine is the second element the name would switch to ending with "ide" and because chlorine is the first element and only has one atom you would not use the prefix "mono." But if the formula is Cl2O then is would be dichloride monoixde because chloride now has two atoms. 

This week I participated a decent amount. I helped my table when we were doing class review but I did not take initiative when writing anything down. I think I could do more to help my table mates such as writing on the board and speaking up in class. I also feel like after reviewing in and out of class I really understood this material. I found it helped me to take extra notes in my journal to emphasize important points that I forgot. Because I felt I had a good understanding of the lessons I tried to help some people from other classes who needed my help understanding the differences in naming ionic and molecular compounds. 

I still need to work on understanding J.J. Thomson's conclusion that because the cathode rays must be stuck together they must be negative. I wasn't really sure how he came to that conclusion or what it meant/what its importance was. A question I still have is how is this information relevant to everything else we learned this week?

I would rank my understanding of this week as a nine out ten because for the most part I understood the rules for each type of ion and how to apply that to solving actual problems. Yet there were still concepts that didn't deal with naming that still confuse me.