Key idea
Alpha decay
Décroissance α : A → A−4 et Z → Z−2
Alpha decay is a nuclear transformation in which an unstable nucleus emits an alpha particle, a helium-4 nucleus containing two protons and two neutrons.
Alpha decay
The key idea
Alpha decay is a nuclear transformation in which an unstable nucleus emits an alpha particle, a helium-4 nucleus containing two protons and two neutrons.
Why it matters
The parent loses two units of atomic number and four units of mass number, giving a simple conservation check for nuclear equations.
A picture to remember
Key idea
Alpha decay
Guided example
Alpha decay
Alpha decay is a nuclear transformation in which an unstable nucleus emits an alpha particle, a helium-4 nucleus containing two protons and two neutrons.
Put it into practice
Alpha decay
Choose a concrete case linked to Alpha decay. Write down the known information, what you are trying to find, and the units. Then state the rule, model or trend you will use. If a calculation is involved, keep the units visible at every line; if it is conceptual, state what changes and what remains fixed.
Check your answer
A strong answer contains four things: the starting situation, the variable that changes, the direction or numerical result, and one check. The check can be a unit, an order of magnitude, a limiting case or a comparison with a familiar example.