Atoms are the building blocks of the universe. Everything is made up of atoms and atoms are extremely small. In fact, there are millons of atoms lurking in the period at the end of this sentence. The most common atoms are hydrogen and oxygen. These atoms are gases that make up most of the air we breath.
Carbon is also a very common atom and it helps to make up the solid backbone of living things.
Atoms have electrical charges that cause them to push away from each other or to bond together. If you put the north end of a magnet next to the south end of a second magnet, you will find they pull together due to magnetic attraction. If you put two north ends together, they will push away from each other. This is similar to what happens when two atoms come together. They will pull together or remain apart.