Question

what is an atom and how big are atoms

Answer 1

The building block of matter is known as atom.

Answer 2

$\huge{Answer}$

Atom is the smallest component of an element. Its the particle of matter that uniquely defines achemical element. These are composed of electrons and a nucleus. 

Atoms are very very small. They are very smaller than anything that can compare with. An atom is a million times smaller than the thickest human hair. 

The diameter of an atomranges from about 0.1 to 0.5 nanometers. The element oxygen contains the atoms with eight protons. And the element gold contains atoms with 79 protons.