Chem Blog #3

1. Max Planck's hypothesis was that energy is released or absorbed in small packets called photons and that only certain energy values are possible. He also said that Energy(E) is equivalent to Frequency(v) multiplied by a Constant(h). This helped Bohr with his model of the atom because, in Bohr's model of the atom, electrons orbit the nucleus in specific pathways that have specific energy levels. There are only certain energy levels that an electron can travel in. Shown below is a picture of Bohr's model with Planck's equation next to it. It shows the different levels that electrons can travel on. Personally, I can compare this to a radio. You aren't able to pick up certain stations, so you can only be on specific stations when you're in a certain area. Just like there are only specific levels that the electron can be on in certain atoms.

2. JJ Thomson's Plum Pudding Model said that atoms were like plum pudding. The pudding part represented a positively charged section of the atom and there were little chunks of negatively charged electrons floating around. This was discovered using that Cathode Ray Tube Experiment which helped Thomson determine that there were negatively charged particles in atoms. The Plum Pudding Model was discarded due to the Gold Foil Experiment which revealed that an atom is mostly made up of empty space. The next experiment used was the Millikan Oil Drop Experiment which helped to determine the mass and charge of single electrons. This led to the Rutherford Model of the Atom. Rutherford's model was that there is a positively charged center and there are electrons orbiting randomly around the center. This was discarded because scientists reasoned that, in this hypothetical model, electrons would lose energy and crash into the positively charged nucleus. Thus came the Bohr Model which, as stated previously, came into being with the help of Max Planck's hypothesis that energy is released or absorbed in small packets called photons. The Bohr Model shows a positively charged nucleus with electrons orbiting around it in specific, neat paths with specific amounts of energy. The Bohr Model wad discredited because there was no possible way to determine the orbit of an electron so therefore the speed and position bust be random. After this, the Wave Model was hypothesized. In this model, there is a small, positively charged nucleus with electrons moving about in orbitals. This model also suggested that electrons release waves as they move. Part of this model was discredited when Henry Moseley discovered the Atomic Number which suggested that there was something missing. James Chadwick then discovered the neutron- a positively charged subatomic particle that's about the same size as a proton. Shown below are the first and the current models of the atom. You can see there is a lot that has changed since the first discovery of the atom. I remember learning about this in physical science my freshman year. We didn't go very in depth, but the basic knowledge I learned then has made it easier for me to remember how the model of an atom has developed.

3.When electrons are excited, they can jump to a higher energy level on an orbital. Then when these electrons fall back down a level, they emit a light. How many levels they drop and where they drop from is what determines which color is emitted. Not all colors are possible for every element since, according to Planck's Theory, electrons can only orbit on certain energy levels depending on the atom. When we broke the light-savers, the light emitted was not continuous because the electrons were not continuously being excited. They were only excited when energy was given to it when it was broken. After the electrons fell back down and emitted light waves, there wasn't more energy for them to repeat this unless we would break them again. There are many ways to apply this to my life since everyone uses light throughout their day. The electric bill itself is evidence that it takes energy to produce light. Or if I were to leave the lights on in my car, the battery would probably be dead by morning because the light is caused by energy.

Chem Blog #2

This past week, we learned a lot about reactions. We began by balancing basic equations and learned that we need to balance equations because of the Law of Conservation of Mass which states that mass is neither created nor destroyed. This idea then lead into the concept that there are five different types of reactions that we can determine by simply seeing the reactants of an equation. The five types include synthesis, decomposition, single replacement, double replacement, and combustion. Synthesis is where two reactants combine to make one product, decomposition is where one reactant splits to make two products, single replacement is when a negatively charged ion in a compound is replaced by another negatively charged ion or a positive replaces a positive, a double replacement reaction is where both the positive and the negative switch places, and a combustion (for this unit) is when a compound of carbon and hydrogen reacts with oxygen to make water and carbon dioxide.
 We then conducted an experiment in which we observed multiple reactions between substances. We wrote down the beginning equations and then after the reaction we tested the products with lipid papers to determine where on the pH spectrum they were and burning/glowing splints to test what the gas given off by the product was. If the lipid paper turned blue, we knew it was a base and if it turned red we knew it was an acid. This helped up determine the resulting compounds. If a glowing splint reignited, we knew the gas was oxygen, if a burning splint went out, we knew the gas of carbon dioxide, and if the burning splint made loud popping noises, we knew the gas was hydrogen. We then labeled which reaction occurred. We also, as a class, observed the reaction that takes place between copper and silver nitrate.

We then went more in depth with the single replacement reactions. We learned that certain elements are more reactive than others. Therefore, sometimes single replacement reactions cannot occur. We conducted a lab in which we placed different metals in aqueous solutions of different metals and observed when a reaction did or did not occur. By looking at our results, we were able to deduce that magnesium was very reactive in comparison to the other metals, and that copper was not very reactive in comparison.
I participated well in the learning process this week. I was gone for a few days, but my lab partner caught me up on many of the main ideas of the days that I missed so I don't have many questions. One question that I do have is- What other kinds of combustion reactions are there? I think I would rate my understanding of the ideas from class this week as a nine out of ten. I am pretty confident that I comprehend most of what had happened, but there can always be places where I'm not 100% sure I know everything. I think I still need to work on remembering the names of some of the chemical reaction types and exceptions to the single replacement reactions.

Chemistry Reflection Blog #1

          In this past week of Chemistry, we learned a lot about air pressure. Early on in the week, we did an experiment similar to the one show in the picture below. But instead of a balloon and books, we used a large plastic bag and a classmate. My fellow classmates and I blew air into the bag and eventually got our peer off the ground. Luckily, there were only a few minor holes that were easily fixed by duct tape. We also observed an experiment involving soda cans exploding due to certain conditions because of air pressure. Another air pressure related experiment was the juice pouch one. We had to draw a particle diagram of how a straw works. After the real world applications, I learned about how to mathematically determine what air pressure is using open and closed manometers, and how to convert between different units of measurement for air pressure. Personally, I really enjoy math and figuring out equations, so that part was fun. Overall, each experiment explained different things about air pressure to me. I learned that many things affect air pressure, such as temperature, altitude, volume, whether the container is sealed or not, and the amount of gas in the container. When the temperature increases, the speed of the particles also increases which causes them to push more on the container they're in and expand. This was shown in the soda can experiment as well as the plastic bag experiment. Whether or not the container is open affecting air pressure was demonstrated when we learned about manometers (shown in pictures below) and the equations for figuring out the air pressure. I found that it's a lot more work (but apparently more inexpensive) to use an open manometer.