radioactivity

Radioactivity

Key terms

• Atom• Nucleus• Protons• Neutrons• Ions• Atomic number• Mass number• Radioactive• Radiation• Alpha particle• Beta particle• Gamma particle• Ionising power• Isotope• Half-life• Penetration• Deflection/ deflected

Radioactivity: industrial applications

What is radiation?

The nuclei of some atoms are unstable. In order to achieve stability they emit radiation.These materials are called radionuclides.They are radioactive.

Radioactivity is a nuclear process – it is not a chemical process. It is not possible to control the rate of radioactive breakdown of a nuclei, it is a random process

Background radiation

Atomic structure

Atoms consist of a nucleus and electronsThe nucleus is made up of protons and neutrons

Blockbusters game

Characteristics of alpha, beta and gamma radiations

There are three types of radiation that can be emitted from a nucleus of an unstable atom.

Alpha (α)and beta (β) are particles of matterGamma (γ) rays are photon of electromagnetic radiation, with a higher frequency than an x-ray.

Characteristics of alpha, beta (β+ and β–) and gamma radiations

Particle Constituent Charge MassAlpha (α) Helium nucleus

2 protons and 2

neutrons

+2 4

Beta- minus (β-) Electron -1 Negligible

Gamma (γ) Short-wave, high

frequency em wave

0 0

Particle Ionising Range Speed Affected by

magnetic field?

Alpha (α) Strong –easily pull

electrons off atoms

(10 000 ionisations

per particle)

Slow Yes

Beta- minus (β-) Weakly (100 atoms

per particle)

Fast Yes

Gamma (γ) Very weakly Speed of light No

Gamma radiation spreads out very quickly. Its intensity decreases by the inverse square law.

Characteristics of alpha, beta (β+ and β–) and gamma radiations

• The half-life of a radioactive isotope is defined as the time it takes for the number of nuclei of the isotope in a sample to halve or the time it takes for the count rate from a sample containing the isotope to fall to half its initial level.

Half-life