What are atoms?
An atom is the smallest particle of matter. Everything, from the smallest salt molecules, to the largest planets are made of atoms.
The term atom is usually used interchangeably with the term element. This is because atoms make up elements and the only thing inside of an element are the atoms of that element.
Atoms are believed to be shaped a lot like the solar system. The nucleus is the center part. It is here where protons and neutrons are located. Protons are positively charged (Yes, I am sure!) and neutrons have no charge. Surrounding the nucleus are the electrons in a structure called the energy cloud or energy rings. It is the number of protons within the nucleus that determines which atom is being referenced. This is called the atomic number.
Atoms are far too small to ever see, so you just have to take science's word they exist.