P2.6 Radioactivity

Question 1

What causes background radiation?

Answer 1

radioactive substances in the environment or from space or from devices such as X-ray machines

Question 2

How was the nucleus discovered?

Answer 2

Rutherford fired alpha-particles at a thin gold foil, discovering that the nucleus exists
the experiment shows that this centre is:
massive(most mass is here) as particles bounced back
positive as some are deflected
small as only a few hit
most of the atom is empty as most go through

Question 3

What are the three types of radiation?

Answer 3

Alpha, Beta, Gamma

Question 4

Explain alpha radiation

Answer 4

2 protons and 2 neutrons- helium nuclei
charge: +2
can be stopped by a few cm of air or by a piece of paper
moves slowly (large mass) 
ionising

Question 5

Explain beta radiation

Answer 5

a neutron turns into a proton inside nucleus and gives off an electron
charge: -1
can be stopped by a thin sheet of aluminium
moves fast(electron is small and light)
ionising

Question 6

Explain gamma radiation

Answer 6

NOT a particle- high energy EM waves that travel at spped of light
charge: 0
can only be stopped by very thick piece of lead or concrete
weakly ionising - has no charge or mass

Question 7

What is an isotope?

Answer 7

have the same number of protons but different numbers of neutrons therefore have same atomic number but different mass numbers

Question 8

What is half-life?

Answer 8

the average time it takes for the number of nuclei in a radioactive isotope to halve

Question 9

What should radioactive tracers be?

Answer 9

beta or gamma emitters that last long enough to monitor but not too long

Question 10

What is radiocarbon dating?

Answer 10

a way of working out how old objects are by measuring how much radioactive C-14 they have left in them