the central part of an atom which contains protons and neutrons

the term for particles in a nucleus (protons and neutrons)

the number of protons within a particular nucleus

the total number of nucleons within a particular nucleus (protons + neutrons)

atoms of the same element with differing numbers of neutrons

Unstable nuclei

Physics

In A-level physics, some pupils will build on this knowledge to learn about probability and half-life equations, nuclear instability, Einstein’s equation E = mc2 that links mass and energy, and controlled nuclear fission.

In the Periodic table unit, in chemistry, pupils learnt about the nuclear model of the atom, the atomic number and mass number, and about isotopes of elements.

Nuclear physics

the central part of an atom that contains protons and neutrons

the total number of protons + neutrons within a particular nucleus

Match each key word or phrase to the correct definition.

Which of the following particles has the smallest mass?

Z shows the number of protons in the nucleus

Z shows the number of neutrons in the nucleus

A shows the number of protons in the nucleus

A shows the number of neutrons in the nucleus

A shows the total number of protons and neutrons in the nucleus

Nuclei can be represented by nuclear notation ($$^{\text{A}}_{\text{Z}}$$X). For example, $$^{21}_{10}$$Ne.
Which of these statements about this notation are correct?

A sulfur atom is represented by the symbol $$^{34}_{16}$$S. Which of these statements are correct?

Neutrons are more stable when close to a proton inside a nucleus.

Neutrons are less stable when close to a proton inside a nucleus.

Neutrons are much more massive than protons.

Neutrons and protons have similar masses.

Which of these statements about neutrons are correct?

They all have 3 protons in their nucleus.

They all have 4 neutrons in their nucleus.

They all have the same number of electrons.

There are 13 known isotopes of lithium. The most common is lithium-7, which can be represented as $$^{7}_{3}$$Li.
Which of these statements about the nuclei of other isotopes of lithium are correct?

Which of these are examples of natural sources of background radiation?

Which of these devices is used to detect nuclear radiation?

The figure shows a model of the atom developed by JJ Thompson. It is the {{}} model of the atom.

Which particles did Rutherford use in his experiment which led to the development of the nuclear model of the atom? 

the nucleus has most of the mass of the atoms

Which of these are conclusions from Rutherford’s scattering experiment?

the discovery of electrons around the nucleus

the energy level (shell) structure of electrons in atoms

Which of these refinements of the nuclear model is Niels Bohr responsible for?

This lesson will be removed by end of Summer Term 2025.

Unstable nuclei

Lesson outcome

This lesson will be removed by end of Summer Term 2025.