Topic 1: Matter And Radiation

Question 1

Nucleon

Answer 1

A neutron or a proton in the nucleus

Question 2

Atomic number

Answer 2

The number of protons in the nucleus of an atom, also the order number of the element in the periodic table

Question 3

Isotopes

Answer 3

Of an element are atoms which have the same number of protons in each nucleus but different numbers of neutrons

Question 4

Nucleon number

Answer 4

Mass number - the number of neutrons and protons in a nucleus

Question 5

Nuclide

Answer 5

Nucleus of an isotope labelled using the isotope notation

Question 6

Specific charge

Answer 6

Charge/mass value of a charged particle, the ratio of charge to mass

Question 7

Strong nuclear force

Answer 7

Force that holds the nucleons together. It has a range of about 2-3fm and is attractive down to distances of about 0.5fm. Below this distance, it is a repulsive force

Question 8

Alpha radiation

Answer 8

Particles that are each composed of two protons and two neutrons
An alpha particle is emitted by a heavy unstable nucleus which is then less unstable as a result
Alpha radiation is easily absorbed by paper, has a range in air of no more than a few centimetres and is more ionising than beta or gamma radiation

Question 9

Beta-minus radiation

Answer 9

Electrons emitted by unstable neutron-rich nuclei (nuclei with a neutron/proton ratio greater than for a stable nuclei)
Stopped by about 5mm of aluminium, has a range in air of up to a metre and is less ionising than alpha radiation and more ionising than gamma radiation

Question 10

Gamma radiation

Answer 10

Electromagnetic radiation emitted by an unstable nucleus when it becomes more stable

Question 11

Neutrino

Answer 11

Uncharged lepton with a very low rest mast compared with the electron

Question 12

Antineutrino

Answer 12

The antiparticle of the neutrino

Question 13

Electromagnetic wave

Answer 13

An electric and magnetic wavepacket or photon that can travel through free space

Question 14

Photon

Answer 14

Electromagnetic radiation consists of photons
Each photon is a wave packet of electromagnetic radiation
Energy of a photon: E=hf

Question 15

Photoelectric effect

Answer 15

Emission of electrons from a metal surface when the surface is illuminated by light of frequency greater than a minimum value known as the threshold frequency

Question 16

Antimatter

Answer 16

Antiparticles that each have the same rest mass and, if charged, have equal and opposite charge to the corresponding particle

Question 17

Positron

Answer 17

A particle of antimatter that is the antiparticle of the electron

Question 18

Rest energy

Answer 18

Energy due to rest mass m0, equal to m0c^2, where c is the speed of light in free space

Question 19

Antiparticle

Answer 19

There is an antiparticle for every type of particle. A particle and it’s corresponding antiparticle have equal rest mass and, if charged, equal and opposite charge

Question 20

Annihilation

Answer 20

When a particle and a its antiparticle meet, they destroy each other and become radiation

Question 21

Pair production

Answer 21

When a gamma photon changes into a particle and an antiparticle

Question 22

Momentum

Answer 22

Mass x velocity

Question 23

Virtual photon

Answer 23

Carrier of the electromagnetic force; a photon exchanged between two charged particles when they interact

Question 24

Weak nuclear force

Answer 24

Force responsible for beta decay

Question 25

W boson

Answer 25

Carrier of the weak nuclear force; W bosons have non-zero rest mass and may be positive or negative

Question 26

Electron capture

Answer 26

A proton-rich nucleus captures an inner-shell electron to cause a proton in the nucleus to change into a neutron. An electron neutrino is emitted by the nucleus. An X-ray photon is subsequently emitted by the atom when the inner shell vacancy is filled