IG Phy – Radioactive Decay and Half-Life(I)

Radioactive decay involves the emission of ionizing radiation from unstable nuclei.

Both alpha decay and beta decay change the element of the decaying nucleus.

An alpha particle consists of two protons and two neutrons.

Alpha decay decreases the nucleon number by 2 and the proton number by 4.

A beta particle is the same as an electron and is emitted when a neutron changes into a proton and an electron.

In beta decay, the total charge of the nucleus before and after the reaction is unchanged.

Gamma rays are electromagnetic waves emitted by an unstable nucleus and do not change the nucleon or proton number.

The half-life of a radioactive isotope is the time it takes for half of the nuclei in a sample to decay.

The activity of a radioactive source is measured in becquerels (Bq), where 1 Bq equals one decay per second.

After two half-lives, one-quarter of the original radioactive nuclei remain undecayed.