Bohr s model of the atom. Wikimedia Commons (CC BY 4.0)
You can search for a picture of an atom on the internet and you ll find one, even though nobody s actually seen an atom before. But we ve got an estimation of what a single atom looks like because of the work of a bunch of different scientists like Danish physicist Niels Bohr.
Atoms are the building blocks of matter a single atom of any individual element is the most basic entity in nature that still abides by the rules of physics we can observe in everyday life (the subatomic particles that make up atoms have their own special rules). Scientists suspected atoms existed for a long time before they could conceptualize their structure even the ancient Greeks figured the matter of the universe was made up of components so small they couldn t be broken down into anything smaller, and they called these fundamental units