Question

What are the three most common types of radioactive decays? How do they differ? Also how many types of decays are there? Please describe them.

Answer 1

Three most common types

There are three main types of radioactive decay: alpha, beta, and gamma.

Let's pause here a minute to define "decay." When an element decays the parent element's nucleus changes - it will actually decay to turn into a different daughter element altogether! How is this possible? Because during radioactive decay the number of protons in the nucleus can change (I know, right?).

Alpha Radiation/Decay

During Alpha decay an atom spits out two protons and two neutrons from its nucleus. This little bundle is called an "alpha particle."

• Alpha decay usually happens in larger, heavier atoms.
• The symbol looks like Helium because Helium-4 has the same number of protons and neutrons as an alpha particle (no electrons, though).
• Since Alpha particles have two protons and no electrons, they have a net charge of 2+.
• During Alpha radiation an atom's proton count drops by two, and we know what that means - a NEW element is formed!
• Alpha radiation can be stopped by PAPER.

Beta Radiation/Decay

Remember we said a neutron is a proton with an electron attached? In beta decay a neutron sends its electron packing, literally ejecting it from the nucleus at high speed. The result? That neutron turns into a proton!

• Beta decay increases an atom's electron count by 1 (notice the 1- in the symbol).
• During Beta radiation an atom's proton count grows by one. Once again, NEW element!
• Beta radiation can be stopped by WOOD.

Gamma Radiation/Decay

Gamma rays (remember that term from when we studied the EMS?) is electromagnetic radiation similar to light. Gamma decay does not change the mass or charge of the atom from which it originates. Gamma is often emitted along with alpha or beta particle ejecton.

• Gamma radiation can be stopped by LEAD.

Comparison of Alpha, Beta and Gamma Radiation/Decay

The diagram below shows the difference between alpha, beta and gamma particles.

The diagram below should make you think back to the cathode ray tube experiment - notice how the negatively charged beta particles are attracted to the (+) plate while the positively charged alpha particle is attracted to the (-) plate. Since gamma radiation has no charge its path does not bend.

The diagram below shows what materials can block each type of radiation. Notice it's easy to block alpha radiation (paper will do!) but tough to block gamma radiation (you'll need a lead vest).

Mode of decay	Participating particles	Daughter nucleus
Decays with emission of nucleons:
Alpha decay	An alpha particle (A = 4, Z = 2) emitted from nucleus	(A ? 4, Z ? 2)
Proton emission	A proton ejected from nucleus	(A ? 1, Z ? 1)
Neutron emission	A neutron ejected from nucleus	(A ? 1, Z)
Double proton emission	Two protons ejected from nucleus simultaneously	(A ? 2, Z ? 2)
Spontaneous fission	Nucleus disintegrates into two or more smaller nuclei and other particles