Atomic Structure

An atom, the smallest particle of an element that still retains the properties of that element, can be split up into smaller particles. Even long ago, they conceived that the atom could be divided into smaller parts. The problem was that they did not know exactly how they were split up. The ancient Greek philosopher, Democritus, thought that atoms were the smallest form of matter and were , therefore, indivisible. A man named John Dalton also believed atoms to be indivisible. Dalton also believed that atoms could not be created or destroyed.

As the question of how atoms are composed has ben risen many many times; so much that people have tried to explain how atoms look. A man named J.J. Thomson made a "plum pudding" model of what an atom looks like:

As you can see, the positive particles (protons) and the negative particles (electrons) are randomly spread out in the atomic space. Thomson was on the right track, but no cigar. A more accurate model was produced by a man named Ernest Rutherford:

Rutherford proposed that the negatively charged electrons orbited around a positively charged nucleus. While this is very very close, what's missing from this picture? Figure it out? That's right; there are not neutrons in the nucleus.

That's better. The orange, uncharged particles in the nucleus that are with the protons are the neutrons. They have no charge, but they add to the atomic mass of the atom. An atom of an element is characterized by its mass number and its atomic number. The mass number is the average mass of the most commonly found isotopes of an element found in nature. Isotopes are atoms of the same element with a different amount of neutrons. The atomic number is the number of the number of protons in the atom of that element. If two atoms have a different number of protons, they are atoms of different elements. If they have the same amount of protons, but different amount of neutrons, they're isotopes.

Separation of Mixtures Lab

Steven and I produced a mixture composed of plastic boiling stones, iron filings, and calcium chloride. After putting each of the ingredients into a small, plastic tray and weighed each of them. We then mixed them all into a beaker and passed them on to another group to be analyzed. The iron filings weighed 4.23 grams; the plastic weighed 10.01 grams; and the calcium chloride weighed 10.57 grams. Once we poured each of the substances into the glass beaker, we stirred them together with a spatula.

After we passed our beaker mixture to another group, we took another groups mixture and tried to analyze what contents they had included into it. Once we got their mixture, we did our best to separate the plastic boiling stones from the sand. The beaker was wet, so it was difficult to know whether or not they used sugar in their mixture. If they had, it had dissolved in the water. The sand that they had put in their beaker was also wet, so we were unable to properly weigh the sand by itself. Once we had separated the ingredients of their mixture, we weighed the plastic at 3.87 grams and the wet sand at 13.21 grams. Once we separated the sand from the sugar using a paper filter and running water, we estimated the weight of the sugar to total at 0.12 grams.

By going through the process of separating each of the individual components of the other groups mixture, we were able to understand how different ingredients can add up to a different weight. While there were larger pieces of plastic, the smaller wet sand weighed more. We also learned that we can separate a small granular ingredients (like sugar) from larger granular ingredients (like sand) using a sort of filter.

Part II
In the second part of this lab, we learned the effects of water on solution when spreading across a paper filter. Before we did anything with the water, we drew different patterns on our pieces of filter paper with different colors of ink. Then, we poked a small hole through the center of the filter and put a small, rolled up pice of paper towel through the hole. After our filter papers were good to go, we filled a small dish halfway with water. Once there's water in the dish, we put our filter papers on top of the dishes, face up, with the small piece of paper towel in the water. As the small piece of paper towel sat in the water, the water slowly made its way up the paper towel and through the filter. As the water spread across the filter, so did the ink. Colors like green broke into yellow and blue as the water spread across. As this went on, the darker colors spread toward the edge with the water while the lighter colors stayed toward the center. This example of chromatography shows that the darker colors on the filter paper are more proved to be carried away by water than the lighter colors. It also showed how colors of ink break apart when water runs through the paper that it's drawn on.