Atom

What Is an Atom?

An atom is a tiny building block that makes up everything around us. It is the smallest piece of matter that still keeps the properties of an element. Atoms are so small that we can't see them with our eyes or even with a regular microscope.

Parts of an Atom

An atom has a center called a nucleus. The nucleus contains protons and neutrons. Around the nucleus, there are tiny particles called electrons that move in a cloud. Protons are bigger than electrons and have a positive charge. Electrons are very small and have a negative charge. Neutrons have no charge but are heavy like protons.

How Atoms Work

Atoms can stick together to form new substances. This is how we get things like molecules and crystals. When atoms join or separate, it causes many of the changes we see in nature. This is what the science of chemistry studies.

Fun Facts About Atoms

Atoms are very small — a human hair is about a million carbon atoms wide! Each atom has a different number of protons, which tells us what element the atom is. For example, all hydrogen atoms have one proton. Atoms can have different versions called isotopes. These have the same number of protons but different numbers of neutrons.