P4 - Atomic Structure

Atom

Same number of protons and neutrons

Ionisation

The removal or addition of electrons to create a charged charged ion

Mass number

Number of protons and neutrons

Atomic number

Number of protons

Background radiation

Constant low level environmental radiation

Isotope

Different forms of an element with the same number of protons but a different number of neutrons

Contamination

Unwanted presence of radioactive atoms

Irradiation

Person is exposed to a radioactive source

Half life

The time taken for half of a radioactive nuclei to decay

Radioactivity is measured in

Becquerels ( Bq )

Radiation dose is measured in

Sieverts (Sv)

Alpha particles: range in air

A few centimeters

Beta particles: range in air

Few metres

Gamma rays: range in air

Great distances

Alpha particles: ionising power

Very ionising

Beta particles: ionising power

Medium

Gamma rays: ionising power

Weak

Alpha particles: penetration power

Paper

Beta particles: penetration power

Aluminium

Gamma rays: penetration power

Thick lead or concrete

What is used to detect radiation?

Geiger-Muller tube

Radioactive decay

Where unstable electrons randomly emit radiation to become stable

What did Rutherford 's experiment prove?

That the atom is mostly empty space with a tiny, dense, positively-charged nucleus

Nuclear fission

One large unstable nucleus splits into two smaller nuclei

Nuclear fusion

Two small nuclei join together to make one large nucleus