What Is an Atom? The Tiny Basic Unit

Understanding What an Atom Is

An atom is the smallest unit of matter that still behaves like the element it belongs to. Everything around you—air, water, objects, and living things—is made of atoms.

The Structure of an Atom

An atom has a central nucleus made of protons and neutrons. Around this nucleus are electrons, which move in regions of space called electron shells.

Why Atoms Are So Small

Atoms are incredibly tiny, far smaller than anything we can see with our eyes. Millions of them could fit inside the head of a pin, yet they form the building blocks of all matter.

How Atoms Form Matter

Atoms join together to create molecules and larger structures. The way atoms connect determines the properties of different materials, from metals to liquids to living cells.

The Simple Takeaway

An atom is the basic unit of everything around us. Tiny and invisible, but essential for forming all matter and making up the physical world.