- Atom = tiny building block of matter that is made up of protons, neutrons and electrons
- Atomic number = the number of protons in an atom
- Compound = atoms of more than one element chemically bonded together
- Density = the measure of the mass of an object divided by its volume (g/cm3)
- Electron = a particle with a negative charge located in the electron cloud
- Mass number = the number of neutrons plus the number of protons in an atom
- Neutron = particle with no electrical charge in the nucleus of an atom
- Proton = particle with a positive charge in the nucleus of an atom
- Element = A substance made up of only one type of atom and can’t be broken down into simpler substances by any normal or chemical means
- Molecule = group of atoms connected by a covalent bond