Balancing a nuclear decay equation (4 marks)

Question: Uranium-238 decays by emitting an alpha particle. Complete the nuclear equation and identify the type of radiation released:

²³⁸₉₂U → ?Th + ?He

State what alpha radiation is and one property. (4 marks)

Mark scheme (4 marks):

• Thorium nucleon number = 234 (1)
• Thorium proton number = 90, helium = ⁴₂He (1)
• Alpha particle is a helium nucleus / 2 protons and 2 neutrons (1)
• Property: highly ionising / stopped by paper / range only a few cm in air (any one) (1)

Full equation: ²³⁸₉₂U → ²³⁴₉₀Th + ⁴₂He