Answer to Question #128785 in Quantum Mechanics for Precious Adeleye

Question

The nucleus of thorium isotope ²³⁴90Th undergoes three consecutive alpha decays . Determine the charge of the resulting isotope

Answer 1

In every alpha-decay the charge of the nucleus decreases by the charge of alpha-particle, so it decreases by 2. The initial charge of the thorium nucleus is 90, so after three alpha decays the charge will be $90-3\cdot 2 = 90-6 = 84$, so we'll obtain a nucleus of polonium. The mass number will decrease by $3\cdot4 = 12.$