Chemistry Entry 8

Our week started with the stressful news that the majority of our class performed poorly on the chapter 6 test, primarily on the "naming ionic compounds" portion. As a a result, we were assigned a series of quizzes focused on each section of chapter six, with the goal to enhance our skills in the subject. We began these quizzes last Tuesday in class, and I have finished all of them except for the last one. The first two quizzes didn't give me that much of a challenge, as they were focused on ionic compounds with both fixed and variable cations. At first I was answering all the questions incorrectly and I kept getting frustrated, but then I realized that the answers I had to type in are case-sensitive, and I was needlessly capitalizing them. The third quiz was slightly harder than the first two, as it focused on polyatomic ions. I always get intimidated when I see a large string of compounds and I overthink what I have to do, which results in mistakes. As long as I stay focused and know that its the same as any other compound, just composed of a larger amount of elements, then I'll be fine.

Phosphate has a charge of 1, not 4! There are 4 oxygens and
1 phosphorus present in phosphate. Having sodium there
threw me off at first.

Quiz 5 was a breeze for me as I'm confident with covalent bond questions, but Quiz 4 was my biggest challenge. Quiz 4 focused on counting atoms, ions, and particles. For the first mini-quiz, I had to redo it twice as I kept misreading the question. I continuously mixed up on counting ions and the # of atoms. I tried to include them together in terms of having the same number for the answer, but  eventually a lightbulb went off and I realized my dingbat mistake. My main issue was forgetting that polyatomic compounds as a whole, have the same charge. There aren't two different charges present in the compound as if that were the case, then the equation wouldn't be balanced. I kept wanting to count the subscript for both categories, which only applies to the # of atoms of the element it's representing. Once I realized this, my percentage didn't drop below a 90% and I felt much more confident on the matter.

Ammonium!! 

On a side note, in general I need to review more on equations involving ammonium, the unique polyatomic ion with a positive charge. Whenever there is a question involving ammonium I always seem to incorrectly answer it, and only correctly answer it if I have previously memorized the answer. Something about it always throws me off, so I'm planning on consistently redoing quiz 4 so as to strengthen my confidence One more thing I'm planning on studying for our upcoming retake, which is also present in quiz 4, are formula units. These mess me up simply because I occasionally incorrectly  balance the charges for the equation, so the then the diagram is incorrect as well. I also need to work on identifying an equation through a given formula unit, as this type of question consistently messed me up on quiz 4. I hope we can go over some of these problems in class this week, as class discussions improve my understanding 99% of the time.

Our first lab we completed in Unit 7 was called the Nail Lab. The purpose of of this was to determine the rate of copper produced to iron consumed in a replacement reaction. Our first step mass our beaker so as our measurements weren't off later on, and then we combined copper (II) chloride with distilled water in our beaker, and began to swirl the contents. I noticed the contents turned an electric blue upon stirring it, but wondered if the color would change as we continued the lab. During this process,

Setting up for the nail lab.

Day 2 of the nail lab.         

my other table members massed out 2 nails together, and then we placed them into the solution. Somewhat true to my prediction, the nail itself reacted by turning a reddish brownish color and it began to crumble. I was surprised to see, in the next day of our observations, that the nails seems to be combined together (as shown below) and the color was a dark green. I also noticed that the reaction between the nails and the copper (II) chloride ceased. My thought process on why this occurred is that all of the iron on the nail must have been used up, so the reaction couldn't continue. This makes sense to me because, when we massed out the beaker and compared it to the previous days, the data showed that all of the iron (Fe) was used up overnight. I love doing these types of labs, especially because I find it so interesting how seemingly normal substances can combine to create an astonishing outcome. To conclude this lab, all table groups compiled their data and recorded them in a table drawn up on the whiteboard, so as to compare results and see how other groups differed from each other.

Combination (synthesis) reaction.

Decomposition reaction.

To finish up the week, our class learned how to balance equations and learned how to describe difference and similarities between various chemical reactions. Funnily enough, the information we covered in the end of the week is the stuff I have to study for the most. In terms of equation balancing, I have a bad habit of overthinking the problem and then coming up with a random answer that doesn't make sense. I figured out that I need to balance off the reaction with the monatomics last, as well as learn to leave diatomics towards the end of the balancing. Remembering to use fractional coefficients first and then multiplying everything so as to make the fraction a whole number is also a section that needs work, which I need to keep in mind as I balance out any future equation. Resuming on Monday, I hope we discuss more as a class on describing chemical reactions and their specific names, as I am completely unfamiliar with this and how to correctly accomplish this. Specifically differences between reactions such decomposition reactions or double replacement ones, as well as the difference between single and double replacement reactions.

I found it really cool that I could tell the reaction was taking
place by the increase in temperature in the beaker!!

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!