P7 radioactivity

Question 1

what is a radioactive substance

Answer 1

contains unstable nuclei that become stable by emitting radiation

Question 2

alpha radiation

Answer 2

stopped by paper
short range in air
most ionising

Question 3

beta

Answer 3

stopped by thin sheet of metal
range of abt 1 m in air
more ionising than gamma
made of fast moving electrons emitted from nucleus

Question 4

gamma

Answer 4

stopped by lead
most penetrating power
unlimited range in air
consists of electromagnetic radiation
can destroy cancer cells in a tumour

Question 5

Isotopes

Answer 5

atoms of the same elements with different number of neutrons

Question 6

ionisation

Answer 6

kills or damages living cells

a , b and g ionise substances they pass through

Question 7

half life

Answer 7

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

Question 8

measuring count rate

Answer 8

count rate after n half lives is

initial count rate / 2^n

Question 9

uses of radioactive isotopes

Answer 9

medical imaging, treatment for cancer, tracers to monitor organs

Question 10

usefulness of ra isotope

Answer 10

half life

type of radiation it emits

Question 11

nuclear fission

Answer 11

splitting of an atom’s nucleus into two smaller nuclei

release of two or three neutrons + energy

Question 12

induced vs spontaneous fission

Answer 12

induced occurs when a neutron is absorbed

Spontaneous occurs w/o neutron being absorbed

Question 13

nuclear reactor

Answer 13

control rods absorb fission neutrons so roughly only one neutron goes on to produce further fission

Question 14

nuclear fusion

Answer 14

forcing nuclei of two atoms close enough together to form a single larger nucleus
energy released when they fuse

Question 15

nuclear waste

Answer 15

many different radioactive isotope that emit nuclear radiation for many years
radiation can cause cancer
must be stores in secure places for many years after unused plutonium and uranium have been removed from it

Question 16

irradiation

Answer 16

the process by which objects are exposed to radiation
( of any type)

Question 17

contamination

Answer 17

when radioactive particles get onto other objects
(isn’t a problem itself, only when materials start to decay and irradiate you)

Question 18

factors for harmfulness of radiation

Answer 18

where you’re exposed to it
type of radiation
amount of radiation you receive
amt depends on - distance from source
- duration of exposure
- how radioactive the source is