Alpha: A Helium nucleus – two protons and two neutrons

Relative mass: 4 Relative charge: +2 Deflection by E/M field: Yes

Ionising power: High Penetrating power: Low Range in air: 5cm Stopped by: Skin, paper

Uses: Smoke detectors, radiotherapy to treat cancer

Danger out of body: Low Danger in body: Cell death, mutation and cancer