Chemistry Entry 7

Metals that form multiple ions.

On Monday our class began a worksheet based on naming ionic compounds. An ionic compound is a chemical compound in which ions are held together in a structure, but contains a neutral charge. The worksheet was specifically focused on expanding our knowledge of the structural units that make up ionic compounds, and using that information to name them. The key to understanding this, for me at least, was keeping in mind that the chemical formulas for any compound must have a net charge of zero, resulting in varying amounts of atoms that need to be added to an equation, so as the formula equals zero. I found this rule confusing at first as I kept failing to make the connection that each element has its own unique charge, and that occasionally ionic compounds (specifically metals), can form multiple ions. To represent this, the roman numeral of the ion used has to be written after the element it is representing, so as the viewer isn't confused if the charges were balanced incorrectly. When I first learned this I thought that the roman numerals were another way to represent the charge of the entire compound, and thought it was an exception to the net charge of zero rule, so I was thoroughly confused on this topic for a day. I finally caught on and ceased to over think the formulas, however it took me a fair amount of practice problems to do so. As I initially struggled with naming ionic compounds, I found that continually practicing these problems, as well as becoming more familiar with a periodic table, was incredibly useful and helped me to master the material by the time the test rolled around. An observation I made while doing additional practice was that the metal is always written first in the formula. I'm wondering if whether or not this a universal rule that was specifically established by a scientist?

Types of ions.

The next day, our class began discussing polyatomic ions, with the lingering question of, can a group of atoms have a charge? A polyatomic ion is a charged ion composed of two or more atoms bonded together, acting as a single unit. These ions differ from monatomic ions, as a monatomic ion is an ion consisting of a single atom. My hypothesis for this question was yes, simply because it didn't make sense to me that an ion wouldn't have a charge, regardless of how many atoms it consists of. On the worksheet accompanying this topic, there was a diagram I found extremely helpful, as it gave example of multiple types of ions. They were then categorized depending on the number of atoms in the ion. Depending on the number of atoms in the ion, the name of the compound changes to fit the amount of atoms. For example, a monatomic ion labelled nitride, can either be called nitrite or nitrate, depending on the number of oxygen atoms present. I had to study this section a fair amount as I was unaware that a change in atoms caused a change in the ionic compounds name. I found that the list of ions in the green booklets we have in class helped me to pinpoint why the names were changed, specifically by looking at the charge and the number of atoms present.

Representing ions and formula units.

The next worksheet our class completed was additional practice on representing ions and formula units. We were given a two different ions, and using that information we had to draw two separate pictures depicting the ions, and then a diagram showing them combined. We also had to write out the actual name of the compound, including the prefixes we learned. Besides balancing the charges, I found that the prefixes gave me the most trouble. The prefixes range from 1-10 (mono-deca), and are used to write out the name of a compound, but only if specific conditions apply. Prefixes can only be used when the ions from covalent bonds, or a bond between two nonmetals. For instance, when combining sulfur and oxygen, the correct name of this compound would be "sulfur trioxide." Tri, or 3, is used as the amount of atoms needed for the net charge to equal zero between the sulfur and oxygen ions is 3 oxygen ions. If the sulfur was replaced with a metal, then "trioxide", or any other prefix that matches with the number of atoms needed to balance the equation, would be incorrect as a bond between a metal and nonmetal is NOT a covalent bond. I initially had trouble with this, as I kept switching around the rule for the prefixes, due to me overthinking it too much. Like before, I resolved this issue through many practice problems.

Additional practice problem.

Finishing up our unit, we were given our review packets to study for the test. The topics I felt the most worried for was the balancing of the charges, and then giving the chemical formula its correct name. To help with my test anxiety, I completed an additional practice worksheet solely based on what I wanted to focus on the most. I found that as I continued to practice these types of problems, it took me less and less time to complete them. The one thing I had to watch out for was accidentally naming an element to be either a metal or nonmetal, when its actually the opposite. I was worried about this because confusing these up could alter your entire answer, as the elements in the compound determine whether or not prefixes are necessary in the equation. Overall I thought that the test went decently for me, although I am slightly worried that I missed a few of the "naming ionic compounds" portion.

My eyes still hurt from this!