Energy is the capacity to do work. Matter has mass and occupies space. All matter is composed of basic elements that cannot be broken down to substances with different chemical or physical properties. Elements are substances consisting of one type of atom , for example Carbon atoms make up diamond, and also graphite.
Atoms are the smallest particle into which an element can be divided.
The ancient Greek philosophers developed the concept of the atom, although they considered it the fundamental particle that could not be broken down. Subatomic particles were discovered during the 1800s. For our purposes we will concentrate only on three of them. The neutron has no charge, and a mass of slightly over 1 amu. Some scientists propose the neutron is made up of a proton and electron-like particle.