Nuclear Equations

Mass and atomic numbers have to balance

• Nuclear equations are a way of showing radioactive decay by using element symbols
• They’re written in the form:atom before decay - atom after decay+radiation emitted
• There is one golden rule to remember:
• the total mass and atomic number must be equal on both sides

Alpha decay decreases the charge and mass of the nucleus

• Remember, alpha particles are made up of two protons and two neutrons. So when an atom emits an alpha particles, its atomic number reduces by 2 and its mass number reduces by 4
• A proton is positively charges and a neutron is neutral, so the charge of the nucleus decreases
• In nuclear equations, an alpha particles can be written as a helium nucleus

Beta decay increases the charge of the of the nucleus

• When beta decay occurs, a neutron in the nucleus turns into a proton and releases a fast-moving electron
• The number of protons in the nucleus has increased by 1. This increases the positive charge of the nucleus
• Because the nucleus has lost a neutron and gained a proton during beta decay, the mass of the nucleus doesn’t charge
• A beta particle is written as 0/-1e in nuclear equations

Gamma rays don’t change the charge or mass of the nucleus

• Gammas rays are a way of getting rid of excess energy from a nucleus
• This means that there is no change to the atomic mass or atomic number of the atom