Definitions
atom
An atom is the smallest unit into which matter can be divided without the release of electrically charged particles.
compound
any substance composed of identical molecules consisting of atoms of two or more chemical elements.
element
a pure chemical substance consisting of atoms that all have the same number of protons in their atomic nucleus, defining its unique atomic number
proton
proton is a stable, positively charged subatomic particle found in the nucleus of every atom, possessing a mass of approximately 1 atomic mass unit (amu)
electron
electron is a stable, negatively charged subatomic particle that exists outside the atomic nucleus, possessing negligible mass compared to protons and neutrons.