Physics A2 Radioactivity

Topics within Specification

• Evidence for the nucleus
• Alpha, Beta and Gamma radiation
• Radioactive Decay
• Nuclear Instability
• Nuclear Radius
• Mass and Energy
• Induced Fission
• Safety Aspects
• Thermal Energy
• Ideal Gases
• Molecular Kinetic theory model

• 1899- Ernest Rutherford discrimated between three types of ionising radiation: alpha, bet and gamma
• in 1909 researchers used alpha particles to fire at gold atoms
• when a beam of positively charged alpha particles is fired at a thin gold film, most will pass through but some are deflected as they pass near to the nucleus
• some particles are deflected by more than 90° so they bounce back
• this evidence means that inside the atoms there must be small positively charged nuclei, which repel the passing alpha particles
• the nucleus must be small since very few alpha particles are deflected by much
• it must be positive to repel the positively charged alpha particles