Dr. Finnan
SG Chem 2
10/29/15
This week in class we continued learning about Unit 6, which is all about the internal structures of particles. The structures of particles is how they get their names and this is what we studied this week in class. POGIL after POGIL we have learned all we need to, to be prepared for our test on Monday. There are different methods for naming different types of compounds. Ionic compounds have a way and molecular compounds have another. Writing the formulas for ionic compounds are a little more complicated to figure out than molecular compounds, so we spent most of the week with those and spent only a little time on molecular compounds. Then we ended the week by reviewing for our test on Monday.
Ionic compounds contain a metal and are held together by ionic bonds. They have specific names for every ionic compound, but there is an easy pattern to figure it out from the formulas of the ionic compounds. If you are given NaCl, for example, you can see that there is a sodium atom and a chlorine atom. The metal is always listed first and the name stays the same, so sodium is still written out as "Sodium." Then instead of writing chlorine as "chlorine" it is written as "chloride." So the whole name of NaCl is "Sodium chloride." Another example is CaS, this is calcium and sulfur, which is written out as "Calcium sulfide." The pattern that you can see here is the the second atom in the compound, the nonmetal, its ending is changes to -ide. This part of naming ionic compounds is very simple. However, there is more; there are polyatomic ions.
Polyatomic ions are a group of atoms that carry a charge. Some examples of polyatomic ions are NO3, CO3, PO4, and C2H3O2. The names of these are nitrate, carbonate, phosphate, and acetate. We were not required to memorize all of the polyatomic ions and were provided with a sheet that had them listed for the test. If you had an ionic compound with a polyatomic ion in it, it is pretty simple to name. For example, BaSO4 this is barium and sulfate compounded together, and the name is simply written as "Barium sulfate." Naming ionic compounds is not difficult, but writing their formulas from their names is a little trickier.
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| This picture is of three problems that our group white boarded out. It shows two different atoms and we were directed to write out the formula and name of the ionic compound formed by the two given atoms in each problem. We also drew out underneath the formula units and what the compound would look like. |
It is important to remember that the net charge of the compound has to equal zero. We were not required to memorize the charges of each atom and polyatomic ion and were again provided with a sheet that listed them for us to use on the test. An example of writing the formula of an ionic compound from it's name is this, you are given Potassium permanganate, the symbol for potassium is K and the symbol for permaganate is MnO4. The formula for this one is simple because the charge of potassium is 1+ and the charge for permanganate is 1- so they cancel out and equal a net charge of zero, the formula is KMnO4. Another example is Copper (II) nitrate, the symbol for copper is Cu and the symbol for nitrate is NO3. This one is a little more complicated because copper has a varible charge and the roman numerals in parentheses indicates what charge it has, in this case copper has a charge of 2+ and nitrate always has a charge of 1-. This means that the formula must be written this way: Cu(NO3)2, to make the net charge of the ionic compound equal to zero. The same thing is done with writing the formulas of molecular compounds.
Molecular compounds are made up of all non-metals held together by covalent bonds. When writing out the names and formulas of molecular compounds it is fairly straight forward. When naming molecular compounds prefixes are added depending on the number of the atom in the compound. An example is IF7, which is written out as "Iodine heptaflouride." Just like in ionic compounds, the second atom in the compound ends in -ide. Another example is P4O10, and is written out as "Tetraphosphorus decoxide." An impotant thing to notice and remember is that when a prefix is added to oxygen the vowel on the end of the prefix is dropped and then added to the front of oxygen. All of the prefixes are mono- (1), di- (2), tri- (3), tetra- (4), penta- (5), hexa- (6), hepta- (7), octa- (8), nona- (9), and deca- (10). This is important to know when writing the formula of a molecular compound when given its name. An example of this is Tribromine octoxide, the formula for this would be Br3O8. Another example is Chlorine monoflouride, the formula for this would be ClF. After doing these, we ended the week by reviewing for the Unit 6 test.
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| This picture is of two problems from one of the POGILs that our group white boarded out. In problem 20, we analyzed the compound (NH4)3PO4 by looking at the number of each element in the compound. In problem 21, we broke down the compound in the first part, then in the second part we talked about what was wrong with the student's formula that was given. |
While reviewing we looked back on the experiments of J.J. Thomson and out Sticky Tape lab. We also continued practicing naming and writing the formulas for ionic and molecular compounds. Among some other things we looked at these all in preparation for our Unit 6 test on Monday, and I feel confident that I did well.
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| In this picture, Dr. Finnan is holding up a flame to a sheet of copper to show the change in the metal as the heat is applied. The color of it changes and the flame appears to be green, but when the flame is pulled away and heat is no longer being applied the color of the copper sheet returns to how it was originally. |
