An element is a general name given to over a hundred and six substances found on earth. An atom is the smallest part of an element that can combine with other atoms. You can compare this to our alphabet. In our alphabet we have a set number of symbols, each with their own characteristics. If one element is similar to one alphabet symbol, for example, T's, then an atom would be a single t. Here's another way to describe it. If you took a piece of aluminum, and kept breaking it down into smaller and smaller pieces, you eventually come to a tiny, microscopic piece. If you tried to divide that tiny piece again, it would no longer show the properties of aluminum. That is an atom.

Let's explore a little bit more about atoms. We have known about atoms since as early as 450 BC. Atoms are made out of three parts. In the middle, you find the protons and neutrons. They form what is called the nucleus. Normally, these don't change much, but on occasion they do. Changes here lead to nuclear power, and can be fairly complex, so we'll skip that for now. Floating around the nucleus are the electrons. The electrons are very important. Chemistry is the science of how atoms and molecules share, shuffle, and exchange electrons. These are the things that decide whether a reaction will happen, whether there'll be energy or light, or even explosions.

Electrons arrange themselves in different ways around the nucleus, and how they do this affects how stable that atom is. Stability is very important to atoms. They will do whatever they have to do become stable. Think of the electrons as staying in an apartment complex that has multiple levels. If you have one electron per room, the atom is happy and stable. If you have even one too many or too few on any level, it works hard to change that. If they have to join with another atom, they will. Sometimes, they will even donate or grab electrons to become more stable.

An atom that has changed the number of electrons it is supposed to have is called an ion. Ions cannot exist in air. Usually, they are in a liquid such as water. Ions are generally fairly stable in the right conditions. Let me give you an example. If one atom of table salt (sodium chloride) is put in water, it forms 2 ions, sodium and chlorine. Sodium has one more electron that it takes to make it really stable. Chlorine is one electron short of being really stable. This is why they join up so well. When that is in water, it will form sodium - a borrowed electron, and chlorine + a borrowed electron. Since these are oppositely charged, they still attract each other, but the water gives them loads of room to roam around, and they are stable enough to do this. This can be really important, as ions conduct electricity well. In fact, learning more about ions is what started the study of chemical electricity. Ions are what conduct the current in certain batteries.

In the electron rearranging is going on constantly. Some of the side effects of this are heat, energy, and light. An imbalance of electrons is what gives us static cling. When we run a plastic comb through our hair, we're changing the balance of electrons. The comb gets more electrons than it wants, and will do strange things to trying to get rid of those. If you've ever held a comb near a slow stream of water, you will see electrons actually pulling the water into a curve in an effort to get rid of its extra electrons. The same thing is happening when you make a balloon stick to the wall by rubbing it on your head. The plastic is trying to give the electrons to the wall.

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