Atoms are the building blocks for everything. Literally. I know that doesn't really help explain, so let me break it down a little. This paragraph is made up work a bunch of sentences. Every sentence is made up of a bunch of words. Every word is made up of letters. Letters are the building blocks for every word we think or say. In the same way, atoms are the building blocks for all of matter. That means that there has to be a bunch of different types of atoms, just like there are a bunch of letters in the alphabet. And, like the alphabet can be used to make millions of words, you can combine these atoms to make all sorts of different type of matter.
If we're talking about different types of atoms, we call them elements. An element is a pure substance, only one type of thing. That means that even if you have 100 atoms of Carbon, its still just the element Carbon. What makes each the element Carbon different from Hydrogen or Oxygen? Good Question! The differences between elements have to do with THEIR building blocks.
If we're talking about different types of atoms, we call them elements. An element is a pure substance, only one type of thing. That means that even if you have 100 atoms of Carbon, its still just the element Carbon. What makes each the element Carbon different from Hydrogen or Oxygen? Good Question! The differences between elements have to do with THEIR building blocks.
Building an Atom
Atoms, all of them, are made up of teeny tiny things called subatomic particles. There are three different types of subatomic particles: protons, neutrons, and electrons. Take a look at the model of an atom below.
![Picture](/uploads/2/0/1/1/20114429/8990744.jpg?417)
See the little colored balls with letters on them? Each of the different colors represents a different type of subatomic particle.
The little red balls with the P on them represent protons. Protons have a positive charge. Protons of a mass of 1 AMU, which stands for Atomic Mass Unit. (Since atoms are so small, there wasn't really anything else to compare them to, so scientists had to make up a new measure of mass only used for atoms.)
The little yellow balls with the N on them represent neutrons. Neutrons are neutral, which means they have no charge to them. Neutrons also have a mass of 1 AMU.
Protons and Neutrons both reside together in the center of the atom, known as the nucleus. See the thin black line surrounding the protons and neutrons in the picture? That line marks the nucleus.
The tiny little blue balls with an E on them represent electrons. Electrons have a negative charge. Notice how much smaller they are than the protons and neutrons? They actually are much smaller, like 1800 times smaller. In the grand scheme of things, they pretty much don't have any mass to them. Instead of being in the nucleus, electrons float around outside the nucleus in what is known as an electron cloud.
Electrons do have a pattern, though, even while floating around in that cloud. They like to float on particular levels, with only a certain amount allowed on each level. You usually won't be asked to deal with more than 3 levels, so let's just look at those:
The little red balls with the P on them represent protons. Protons have a positive charge. Protons of a mass of 1 AMU, which stands for Atomic Mass Unit. (Since atoms are so small, there wasn't really anything else to compare them to, so scientists had to make up a new measure of mass only used for atoms.)
The little yellow balls with the N on them represent neutrons. Neutrons are neutral, which means they have no charge to them. Neutrons also have a mass of 1 AMU.
Protons and Neutrons both reside together in the center of the atom, known as the nucleus. See the thin black line surrounding the protons and neutrons in the picture? That line marks the nucleus.
The tiny little blue balls with an E on them represent electrons. Electrons have a negative charge. Notice how much smaller they are than the protons and neutrons? They actually are much smaller, like 1800 times smaller. In the grand scheme of things, they pretty much don't have any mass to them. Instead of being in the nucleus, electrons float around outside the nucleus in what is known as an electron cloud.
Electrons do have a pattern, though, even while floating around in that cloud. They like to float on particular levels, with only a certain amount allowed on each level. You usually won't be asked to deal with more than 3 levels, so let's just look at those:
The first level only gets two electrons maximum. Once we get to Lithium (which has 3 electrons) we have to add another layer. This layer can have 8 more electrons before it overflows. Then, Sodium (11 electrons) starts another layer, which can also have up to 8 electrons in it. (Don't worry, we'll discuss this more later!)
Building an Element
Now that you have a better understanding of what makes up an atom, let's talk about how we get all the different elements that exist in the universe. So far, there are 118 elements identified on the periodic table (we'll get to that). What makes a hydrogen atom different from Carbon or Oxygen or Chlorine? Each element differs from every other element based on how many protons it has. For example, every atom of Oxygen in the universe has exactly 8 protons. If it had more or less protons, it wouldn't be Oxygen any more.
Now that we know how scientists determine which element is which, let's take a look at how scientists keep track of all those elements.
Now that we know how scientists determine which element is which, let's take a look at how scientists keep track of all those elements.