Topic 7.b : radioactivity

Radioactive

Emitting or relating to the emission of ionizing radiation or particles (alpha, beta, gamma or neutrons)

Nucleus

The centre of the atom which contains the protons and the neutrons

Nuclei

The plural of nucleus

Nucleon

Any particle found inside the nucleus (ie protons and neutrons)

Isotope

An atom of an element with the same number of protons but a different number of neutrons.

Nuclear radiation

Particles released from the nucleus of an atom

Alpha

A type of radiation made up of 2 protons and 2 neutrons. It is released fro the biggest nuclei and is sometimes called a helium nucleus

Beta

A type of radiation made up of a high speed electron. The beta particle is formed when a neutron turns into a proton and an electron. the electron is fired out of the nucleus

Gamma

A type of radiation made up of an electromagnetic wave released from the nucleus It is pure energy and doesn't affect the number of protons and neutrons in the nucleus.

Neutron

A type of radiation sometimes released from the nucleus of an atom. Often released in nuclear fission and fusion

Helium

An elemet contain 2 protons. An alpha particle can turn into Helium when it attracts 2 electrons

Ionise

The process of removing an electron from an atom

Ionising power

The ability of radiation to remove electrons from an atom. Alpha can ionise easily

Penetrate

To move into something

Penetrating power

The ability to move trhough an object. Gamma can easily penetrate most objects

Background radiation

The radiation that is found around us. This does not include any radiation that is produced in an experiment.

Half life

The time it takes for radioactivity to halve/ for half of the nuclei to decay

Artificial

Produced by humans

Contamination

Contamination is when a radioactive material enters an object and releases radiation inside of said object

Artificial sources of radiation (H, NB, NPS)

Hospitals, nuclear bombs, nuclear power stations

Natural sources of radiation (R, F, CR)

rocks, food, cosmic radiation

irradiation

When radiation passes in and out of a substance

Where does radioactivity come from

Radioactive atoms. Isotopes of some elements are unstable because they have too many neutrons.

Why does the nucleus emit radioactive particles or waves

To become more stable

What is the product of aloha radiation

A nucleus and an alpha particle

What happens to mass number after alpha radiation

it decreases by 4

What happens to atomic number after alpha radiation

it decreases by 2

What charge does alpha particles have

Positive

How ionising are alpha particles

Very ionising

How penetrating are alpha particles

Not very penetrating, can be stopped by a sheet of paper or a few cm of air

How ionising are beta particles

Fairly ionising

How penetrating are beta particles

More than alpha - they can pass through paper but are stopped by a sheet of aluminium

What happens to the atomic number of a particle after beta radiation

Increases by one

What happens to the mass number of a particle after beta radiation

Stays the same

When is gamma radiation often given off

After an atom have undergone alpha or beta radiation

What is the product of beta radiation

Particle with an atomic number one higher than the original particle, and an electron

Geiger-Muller tube

Allows a count of the nuber of radioactive particles that enter the tube of the detector to be counted

Photographic film

Can be incorperated into a small device that can be worn to provide an estimate of how much radioactigvity a person has been exposed to

Dangers of ionisation on the body

Ionising radiation can cause mutation in the DNA