Topic 8 - Radioactivity and Nuclear Physics (GCSE Edexcel Combined Physics Retrieval Questions)

What are the relative mass and charge of a proton?

Mass 1, Charge +1

What are the relative mass and charge of a neutron?

Mass 1, Charge 0

What are the relative mass and charge of an electron?

Mass 1/2000, Charge -1

What is the radius of a atom?

10⁻¹⁰m

What is the radius of a nucleus?

10⁻¹⁴m

What is an isotope?

Isotopes are atoms of the same element that have the same number of protons but a different number of neutrons

When an electron absorbs a photon, what happens?

It excites (moves up to a higher energy level)

What was JJ Thomson's plum pudding model?

The atom was thought to consist of negatively charged electrons (the 'plums') in a positively charged 'dough'.

What was concluded due to most of the alpha particles passing straight through the gold foil Rutherford's scattering experiment?

Most of the atom is empty space with most of the mass concentrated in a small nucleus.

What was concluded due to some alpha particles being scattered in Rutherford's scattering experiment?

The nucleus is positively charged.

What was concluded a small number of alpha particles being completely rebounded in Rutherford's scattering experiment?

The nucleus is small, dense and positive.

What did Bohr discover about the atom?

Electrons orbit the nucleus in energy levels.

What is an alpha particle?

A helium nucleus (2 protons and 2 neutrons)

What is a beta - particle?

A fast moving electron

What is a beta + particle?

A fast moving positron

What is a positron?

The anti-particle of an electron (opposite charge and same mass)

Put alpha, beta and gamma in order of their penetration power (high to low).

Gamma, Beta, Alpha

Put alpha, beta and gamma in order of their ionisation power (high to low).

Alpha, Beta, Gamma

What full absorbs: a) an alpha particle b) a beta particle c) gamma radiation

a) a few cms of air or paper b) thick aluminium b) thick lead or metres of concrete

Define background radiation.

The measure of the level of ionising radiation present in the environment

Name the natural sources of background radiation.

Radon gas in rocks, cosmic rays, carbon-14 in living things, food and drink

Name the man-made sources of background radiation.

Medical sources, nuclear waste, nuclear weapons fallout, nuclear accidents

How do you measure radioactivity?

With a Geiger-Müller tube, remove background count.

What happens in during beta minus decay?

A neutron becomes a proton in the nucleus and a electron is emitted

Define activity in radioactivity.

The rate at which the unstable nuclei from a source of radiation decays.

What is the unit for activity?

Becquerel (Bq)

What is half-life?

The time taken for the initial number of radioactive nuclei to decay by halve or for the activity of a source to decay by half

What is the danger of a short half life?

the nuclei will decay very quickly so will emit a lot of radiation in a short amount of time

What is the danger of a long half life?

present a risk of contamination for a much longer time

Which radioactive source is used for smoke detectors and why?

Alpha, because it is blocked by smoke

Which radioactive source is used for thickness monitoring and why?

Beta, because absorption would vary based on how thick the material is

Why is ionising radiation dangerous?

It can mutate DNA which can kill cells or lead to cancer.

How do you handle radioactive sources safely?

Long 30cm tongs, kept in a lead lined container, limit exposure time, wear protective clothing

Define radioactive contamination.

The unwanted presence of materials containing radioactive atoms on other materials

Define radioactive irradiation.

The process of exposing a material to alpha, beta or gamma radiation