Stable and unstable nuclei Flashcards – AQA A-level Physics (7408)

What is alpha decay?

A radioactive transformation in which an unstable nucleus emits an alpha particle containing two protons and two neutrons.

What is the general nuclear equation for alpha decay of a parent nucleus ${}^{A}_{Z}X$?

${}^{A}_{Z}X \rightarrow {}^{A-4}_{Z-2}Y + {}^{4}_{2}\mathrm{He}$

Which two quantities are conserved in an alpha-decay equation?

Mass number and atomic number.

What happens to a neutron in a nucleus during beta-minus decay?

It changes into a proton, emitting an electron and an electron antineutrino.

What is the general nuclear equation for beta-minus decay?

${}^{A}_{Z}X \rightarrow {}^{A}_{Z+1}Y + {}^{0}_{-1}e + \bar{\nu}_e$

Why was the neutrino hypothesised in beta decay?

To account for energy conservation: the electron’s energy varies because energy is shared with the antineutrino and the recoiling nucleus.