7.1 Atoms and radiation

Question 1

What did Henri Becquerel discover about uranium thanks to the photographic film

Answer 1

He realised the uranium salts must have sent out some form of radiation that passed through paper but not metal

Question 2

What test did Rutherford do and what did he discover

Answer 2

• he put different materials between the radioactive substance and the detector
• he discovered that alpha radiation was stopped by paper and that beta radiation went through paper

Question 3

Alpha radiation def

Answer 3

Alpha particles, each composed of two protons and two neutrons, emitted by unstable nuclei

Question 4

Beta radiation def

Answer 4

Beta particles that are high-energy electrons created in, and emitted from, unstable nuclei

Question 5

Gamma radiation def

Answer 5

Electromagnetic radiation emitted from unstable nuclei in radioactive substances

Question 6

Who invented the Geiger counter

Answer 6

Hans Geiger, Rutherford’s research student

Question 7

What did Rutherford go on to propose after he discovered the nucleus

Answer 7

That the nucleus contained protons and neutrons

Question 8

Why are some substances radioactive

Answer 8

• atoms of a radioactive substance have an unstable nucleus
• an unstable nucleus becomes stable (or less unstable) by emitting alpha, beta or gamma radiation
• it is a random event

Question 9

What is decay

Answer 9

When an unstable nucleus emits radiation