31st Dec '25

Atoms and Radiation

The basic structure of an atom is a small central composed of and surrounded by .

Atoms of different elements have different numbers of . The total number of protons and neutrons (nucleons) in an atom is called its mass (nucleon) number.

The atoms of an element always have the same number of , but have a different number of for each isotope.

Some isotopes give out from the of their atoms all the time, whatever is done to them. These substances are said to be .

There are three types of radiation emitted by radioactive sources:

Alpha radiation consists of nuclei, particles made up of two protons and two neutrons.

Beta radiation consists of high-energy (fast moving) emitted from the nuclei of atoms. For each electron emitted, a in the nucleus becomes a .

Gamma radiation is very wavelength electromagnetic radiation. They are similar to x-rays, but come from energy released from an unstable nucleus, while x-rays get their energy from fast moving electrons.