Chemistry deals with atoms, which are composed of subatomic particles that differ in mass and charge. Altering the numbers of these particles can alter the element or the isotope identity of an atom. Here are some subatomic facts:
Subatomic particles:
Proton, p+: 1 atomic mass unit (amu), +1 charge
Electron, e–: 1/1,836 amu, –1 charge
Neutron, n0: 1 amu, 0 charge
Atomic number:
Equals the number of protons
Determines the element
Mass number:
Equals the number of protons plus neutrons
Determines the isotope
