All matter is made up of atoms and there are over 100 different types of atoms.
An element is a substance that only contains one type of atom.
Atoms can combine together to form compounds.
Atoms are made of three particles: protons, neutrons and electrons.
1- Protons have mass and a positive charge.
2- Neutrons have mass and no charge.
3- Electrons have no mass and a negative charge.
Protons and neutrons are in the nucleus and electrons are in the shell orbiting the nucleus.
The atomic number (Z) is the number of protons in an atom and the mass number (A) is the number of protons plus the number of neutrons