Identify the subatomic structure of an atom.

SUBATOMIC PARTICLES

After reading this section you will be able to do the following:

What are atoms made of?

Now that we have talked about how atoms are combined to make other substances, let's talk about the particles that make up the atom. Particles that are smaller than the atom are called subatomic particles. The three main subatomic particles that form an atom are protons, neutrons, and electrons. The center of the atom is called the nucleus. First, let's learn a bit about protons and neutrons, and then we will talk about electrons a little later.

Protons and Neutrons

Protons and neutrons make up the nucleus of an atom. All protons are identical to each other, and all neutrons are identical to each other. Protons have a positive electrical charge, so they are often represented with the mark of a "+" sign. Neutrons have no electrical charge and are said to help hold the protons together (protons are positively charged particles and should repel each other).

If all protons are identical and all neutrons are identical, then what makes the atoms of two different elements different from each other? For example, what makes a hydrogen atom different from a helium atom? The number of protons and neutrons in the nucleus give the atoms their specific characteristics. In the graphic below you will notice that each of the three elements have different numbers of protons and neutrons. They would also like to have the same number of electrons as they have protons in order to stay electrically balanced.