Intro to radioactivity

• Atoms are really, really small.
• The radius of one atom is about 1 x 10-10m.
• The nucleus of an atom is made up of protons and neutrons.
• The nucleus is where most of the mass is concentrated.
• Most of an atom is empty space.
• Electrons orbit the nucleus in energy levels.
• Isotopes have the same number of protons but a different number of neutrons.
• Isotopes are atoms of an element with the normal number of protons and electrons, but different numbers of neutrons.
• When ionising radiation enters the tube it produces ions in the gas.
• The ions created in the gas enable the tube to detect radiation.
• A pulse is produced in the tube for a short time.
• The current produced in the tube is amplified and counted.
• Background radiation comes from sources such as bricks, food, radon gas in atmosphere, cosmic rays, and rocks.
• A radioactive substance contains unstable nuclei (unbalance of protons and neutrons) that become stable by emitting radiation.
• Alpha , Beta  and gamma  are types of radiation emitted during radioactive decay.