Thorium-232 decays by a 10-step series, ultimately yielding lead-208. How many α particles and how many β particles are emitted?

Verified step by step guidance

1. Understand that an alpha (α) particle emission decreases the atomic number by 2 and the mass number by 4.
2. Recognize that a beta (β) particle emission increases the atomic number by 1 without changing the mass number.
3. Start with thorium-232 (Th-232) and note that it decays to lead-208 (Pb-208).
4. Calculate the change in mass number: 232 (initial) - 208 (final) = 24. This change is due to the emission of α particles.
5. Since each α particle reduces the mass number by 4, divide the total change in mass number (24) by 4 to find the number of α particles emitted.

Key Concepts

Radioactive Decay

Radioactive decay is the process by which unstable atomic nuclei lose energy by emitting radiation. This can occur in various forms, including alpha (α) and beta (β) decay. In alpha decay, an atomic nucleus emits an alpha particle, consisting of two protons and two neutrons, while beta decay involves the transformation of a neutron into a proton or vice versa, emitting a beta particle (electron or positron). Understanding these processes is crucial for analyzing decay series.

Decay Series

A decay series is a sequence of radioactive decay events that an unstable nucleus undergoes until it reaches a stable state. Each step in the series may involve different types of decay, leading to the formation of intermediate isotopes before arriving at a stable end product. In the case of thorium-232 decaying to lead-208, the series involves multiple alpha and beta decays, which must be accounted for to determine the total emissions.

Alpha and Beta Particles

Alpha particles are positively charged particles that consist of two protons and two neutrons, effectively reducing the atomic number of the parent nucleus by two. Beta particles, on the other hand, are high-energy, high-speed electrons or positrons emitted during beta decay, which can change a neutron into a proton or vice versa, altering the atomic number by one. The balance of these emissions is essential for calculating the total number of each type of particle emitted in a decay series.