Chemistry - Radioactivity

Henri Becquerel

discovered radioactivity

Polonium and Radium

were discovered by Pierre and Marie Curie

Radioactivity

the spontaneous breaking up of unstable nuclei with the emission of one or more types of radiation

Alpha Particles

are groups of two protons and two neutrons, i.e. helium nuclei

Beta Particles

are fast-moving electrons

Gamma Rays

are high-energy electromagnetic radiation

Americium-241

a radioactive element that emits alpha particles, and is commonly used in smoke detectors

Geiger-Muller Tube

used to detect radioactive radiation

Alpha Particles

are stopped by a sheet of paper

Beta Particles

can penetrate about 5mm of aluminium

Gamma Rays

are only stopped by a thick block of lead

Nuclear Reaction

a process that alters the composition, structure or energy of an atomic nucleus

Chemical Reaction

1. involves electrons rather than the nucleus

2. no new element formed

3. no release of nuclear radiation

4. chemical bonds broken and formed

Nuclear Reaction

1. changes take place in nucleus and electrons not involved

2. a new element is formed

3. nuclear radiation is released

4. no chemical bond breaking or bond formation involved

Half Life

the time taken for half of the nuclei in any given sample to decay

Radioisotope

a radioactive isotope

Uses of Radioisotopes

• medicine

• archaeology

• agricultural research

• food irradiation

• smoke alarms

• in industry

Radiocarbon Dating

a technique used to determine the age of an object containing carbon

it is based on the ratio of carbon-14 to carbon-12 in the object