Nuclear (Radioactive) Decay

If there is too much energy in the nucleus, some of the energy is pushed out so that the nucleus can become stable (correct amount of energy). The energy that gets thrown out is called radiation.

• It occurs spontaneously, so at any time

• The nucleus becomes lighter

• Sometimes it may even change the number of protons which will change the element the atom is

Types of Decay

Atoms can be unstable for different reasons, so they release energy in the best way for them to become stable. The three different types of decay are called:

• Alpha (α)

• Beta (β)

• Gamma (γ)

Imagine an atom as a heavy suitcase. If it's too heavy to carry, you might take out a couple of big items to make it lighter.

In alpha decay, the atom gets rid of two protons and two neutrons (which are like the big items) all at once. This makes the atom lighter and more stable.

​Alpha Decay

Alpha decay is what occurs when a nucleus breaks down and releases an alpha particle. This is represented with the symbol 𝛂.

An alpha particle is essentially the nucleus of a helium atom (two protons and two neutrons).

​Alpha Decay

In alpha decay, the atomic mass is reduced by 4 (2 protons and two neutrons).

How much does the atomic number reduce by?

​Alpha Decay

Imagine an atom as a sports team with too many defenders. In beta decay, one defender changes into an attacker to balance the team. This switch helps the atom become more stable.

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Beta Decay

Sometimes a neutron is capable of turning into a proton and an electron. The electron is immediately kicked out from the nucleus. This high-speed electron is known as a beta particle. Beta particles are represented with the symbol 𝛽.

When an atom undergoes beta decay, the atomic mass stays the same but the atomic number increases.

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Beta Decay

​The parent nucleus loses an electron, resulting in a proton.

The new daughter nucleus has an additional positive charge but its atomic mass stays the mass stays the same because the mass of a proton is equal to the mass of a neutron.

Beta Decay

Beta Decay

​After an atom goes through alpha or beta decay, it might still have too much energy, like a toy that keeps spinning after you stop pushing it. Gamma decay is when the atom releases this leftover energy in the form of gamma rays. These rays don’t change the atom’s parts, but they help the atom settle down into a more comfortable state.

Gamma Decay

Gamma decay happens when an atom releases extra energy in the form of gamma rays after going through alpha or beta decay. This energy doesn't change the number of protons or neutrons, but it helps the atom settle down into a more stable state. Gamma rays are like a final burst of energy that makes the atom more comfortable.

Gamma Decay

​Read over your notes before we do some multiple choice questions.