The atomic nucleus

The key idea

The nucleus contains protons and neutrons bound by the strong nuclear interaction. Nuclear size, binding and stability depend on the balance of several physical effects.

Why it matters

Nuclear structure explains isotopes, radioactivity, nuclear energy and much of the origin of the chemical elements.

A picture to remember

Key idea

The atomic nucleus

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Key idea

The atomic nucleus

Rayon nucléaire approximatif : R ≈ r₀ A^(1/3), r₀ ≈ 1,2 fm

The nucleus contains protons and neutrons bound by the strong nuclear interaction. Nuclear size, binding and stability depend on the balance of several physical effects.

Guided example

The atomic nucleus

The nucleus contains protons and neutrons bound by the strong nuclear interaction. Nuclear size, binding and stability depend on the balance of several physical effects.

Put it into practice

The atomic nucleus

Choose a concrete case linked to The atomic nucleus. 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.