What are atoms made of?

Atoms are made up of three fundamental particles - protons, electrons, and neutrons. 

Protons are positively charged, heavy particles that are found in the nucleus at the center of the atom. The number of protons in an atom determines the chemical behavior of the element. Electrons are negatively charged, tiny, lightweight particles that surround the atomic nucleus in pathways called orbitals. The inner orbitals surrounding the atom are spherical but the outer orbitals are more complex. Neutrons are uncharged particles that are found in the nucleus of all atoms except hydrogen. The mass of a neutron is a little larger than that of a proton.