Relative mass: Approximately 1 atomic mass unit (amu) or 1.6726 x 10^-27 kg
Neutron

Relative charge: 0 (neutral)
Relative mass: Approximately 1 atomic mass unit (amu) or 1.6749 x 10^-27 kg
Electron
Relative charge: -1
Relative mass: Approximately 1/1836 amu or 9.11 x 10^-31 kg
Charge Neutrality
Atoms are electrically neutral because the number of protons (positively charged) in the nucleus is equal to the number of electrons (negatively charged) in the electron cloud
Radioisotopes
Different isotopes of the same element have the same number of protons in their atomic nuclei but differing numbers of neutrons. Some isotopes of an element are unstable and show radioactive decay.
