SG Chem 2 - Eighth Blog

The last two weeks in chem 2a we did a lot of labs and worksheets to help us get a better understanding of this new unit, unit seven. We also reviewed the unit six material due to the fact that most kids did not seem to understand the material. 

To start learning lesson seven we did a nail lab which required us to mix a copper chloride solution and, in my groups case, one nail (some tables had two or three nails). The goal was to find the ratio of copper produced to iron consumed.

Day 1: The copper chloride before adding 50mL of distilled water

Day 1: Copper Chloride with 50mL of distilled water

Day 1: Nail added to copper chloride solution

Day 2: The nail in the copper chloride 

Day 2: Draining the copper chloride (our nail fully dissolved)

This lab was done over the course of three days and on the third day we took all the information and compared it to the other groups data. We found that for all the groups, no matter how many nails they had, the ratio for moles of copper:moles iron was 1:1.   

That same week we started practicing balancing chemical reactions. A key piece of information from this was that to balance these reactions you needed to balance the amount of atoms, not the number of coefficients. We did a lot of different practice sheets on balancing equations and I think after the first few sheets I was able to get the hang of balancing the equations. Some took longer than others, but I really enjoy these types of problems because it's like a logic puzzle.

Later we did another lab called Describing Chemical Reaction. For this there were about 10 stations that we rotated around to complete a different task. We would observe the reaction between two different chemicals and then later would balance the equations out. I found that lab a lot of fun because there were so many different things to do and all of them were slightly different yet all showed the same basic idea - that when two elements react they may change form but the amount of each elements atoms will stay the same from beginning to the end.

The last two weeks I felt like I really understood the material. Balancing reactions was pretty simple, even though some were more complex than others, the labs were fun and informing, and the class discussions helped to reiterate some of the ideas from unit 6. Something that I did not understand was the patterns of chemical reaction. This was a sheet that we started Friday of this week so it is a rather new concept. We have not been able to talk as a class about these so I'm hoping that that will be able to explain some things to me. I don't understand the differences between some of them or what the point of them are. Overall I think I'd rate my understanding of the past two weeks as a 9/10 just because I understood everything but that patterns in chemical reactions.

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.