Basic Model of the Atom

• All matter whether gas, liquid or solid is composed of atoms.
• Atoms consist of a nucleus made up of protons and neutrons
• The nucleus of each atom is surrounded by electrons occupying orbits or shells.
• The number of electrons equals the number of protons in an electrically neutral atom
• Each element consists of atoms with a unique number of protons in its nucleus, for example
• The element Hydrogen (H) has only one proton in its atomic nucleus.
• The element Lead (Pb) has 82 protons in its atomic nucleus.