Sub-atomic particles

• The radius of a nucleus is less than 1/10 000 of that of the atom (about 1 x 10–14 m).
• Proton has a relative mass of 1 and a relative charge of +1
• Neutron has a relative mass of 1 and no charge.
• Electrons relative mass is very small and has negative charge of (-1)
• The number of protons in an atom of an element is its atomic number. All atoms of a particular element have the same number of protons. Atoms of different elements have different numbers of protons
• In an atom, the number of electrons is equal to the number of protons in the nucleus. Atoms have no overall electrical charge.
• Protons have a positive charge but atoms have no overall charge that is because the number of protons is equal to the number of electrons