P6 RADIOACTIVITY

Question 1

how can atoms of the same element differ in nuclear mass?

Answer 1

they have different numbers of electrons

Question 2

what can unstable nuclei emit?

Answer 2

alpha particles, beta particles, gamma radiation and neutrons

Question 3

when radiation is released by nuclei, what also changes?

Answer 3

there are changes in the mass, charge of a nucleus or both

Question 4

how can you check a balanced equation for radioactive decay is correct?

Answer 4

top numbers add up and bottoms numbers add up

Question 5

how are electrons arranged differently in each atom?

Answer 5

in each atom, electrons are arranged at different distances from the nucleus

Question 6

what can cause electron arrangement to change?

Answer 6

absorption/emission of EM radiation

Question 7

what can happen to inner electrons when they absorb energy from radiation?

Answer 7

become ‘excited’ and rise to a higher energy level. when this energy is lost by the electron it is emitted as radiation

Question 8

what is ionisation?

Answer 8

when outer electrons are lost

Question 9

what can happen if the nucleus of an atom changes?

Answer 9

can cause absorption or generation of EM waves esp gamma ray emission

Question 10

what is a half life?

Answer 10

average time taken for the activity of a sample of unstable nuclei to halve

Question 11

what is the net decline?

Answer 11

ratio of final to initial activity

Question 12

what are the differences in penetration between alpha particles, beta particles and gamma rays?

Answer 12

alpha particles have the shortest range and can be stopped by skin/paper. beta particles have a larger range and is stopped by aluminium. gamma rays have the longest range and are stopped by thick lead

Question 13

what’s the difference between irradiation and contamination?

Answer 13

contamination is when there’s radioactive material inside the body or on the skin. irradiation happens when there’s radioactive material outside the body but it can travel into the body

Question 14

what are the differences in hazards associated with contamination + irradiation?

Answer 14

irradiation is temporary: if the source is taken away, irradiation stops but contamination lasts longer bc if the source is taken away the atoms causing the contamination are left behind

Question 15

why do the hazards associated with radioactive material differ according to the half life involved?

Answer 15

a longer half life means a substance is radioactive for a v long time, so it is more dangerous

Question 16

describe uses of nuclear radiation for exploring internal organs

Answer 16

gamma rays can be used to explore internal organs because of their weak ionising power- can consume radioactive tracer which releases gamma rays

Question 17

how can nuclear radiation be used to control or destroy unwanted tissue?

Answer 17

gamma knives can be focused onto a cancer tumour

Question 18

what is nuclear fission?

Answer 18

when unstable nuclei split

Question 19

what has to happen before fission can occur?

Answer 19

the unstable nucleus must first absorb a neutron

Question 20

what is nuclear fission used for?

Answer 20

releasing energy from large, unstable nuclei but splitting them into smaller nuclei

Question 21

what’s a chain reaction?

Answer 21

when a neutron starts a fission reaction, but other neutrons are also formed

Question 22

what is released during nuclear fission?

Answer 22

energy in the form of heat and radiation

Question 23

describe the process of nuclear fusion

Answer 23

2 light nuclei merge to form a heavier nucleus. energy is released (as radiation) because total mass of the nucleus formed is less than the mass of the 2 original nuclei (the leftover mass becomes energy)