Protons: mass of 1, relative charge of +1
Neutrons: mass of 1, relative charge of 0
Electrons: mass of 5.4x10-4, relative charge of -1
mass number: total number of protons plus neutrons.
atomic number is the number of protons in the nucleus.
isotopes: elements of the same number of electrons and protons (same atomic number) but different mass number, so different number of neutrons.
number of neutrons = mass number - atomic number.
properties of an isotopes:
- same atomic number
- different neutron number
- rate of diffusion is different
- different …