Radioactivity

Question 1

who discovered radioactivity

Answer 1

Henri Becquerel

Question 2

how did henri becquerel discover radioactivity?

Answer 2

while studying uranium salts

Question 3

what did the curies (mary + pierre) discover?

Answer 3

2 new radioactive elements: polonium and radium

Question 4

what is alpha decay

Answer 4

helium nucleus

Question 5

what is beta decay

Answer 5

fast moving electrons

Question 6

how is beta decay formed

Answer 6

when a neutron is converted into a proton and an electron, and the electron is ejected from the nucleus

Question 7

what is gamma decay

Answer 7

high energy electromagnetic radiation

Question 8

what is alphas penetrating power

Answer 8

low- penetrates up to a sheet of paper/air

Question 9

what is betas penetrating power

Answer 9

medium: penetrates up to 5mm of aluminium

Question 10

what is gammas penetrating power

Answer 10

high-can penetrate up to a thick piece of lead

Question 11

what is the mass of alpha

Answer 11

heavy

Question 12

what is the size/mass of beta

Answer 12

light

Question 13

what is the mass of gamma

Answer 13

not applicable as it is not a particle so it has no mass

Question 14

what is the speed of alpha

Answer 14

slow (slowest of the 3)

Question 15

what is the speed of beta

Answer 15

fast (faster than alpha

Question 16

what is the speed of gamma

Answer 16

very fast: fastest of the 3

Question 17

how does alpha deflect in a magnetic field

Answer 17

attracts to negative plate

Question 18

how does beta deflect in a magnetic field

Answer 18

attracts to positive plate

Question 19

how does gamma deflect in a magnetic field

Answer 19

no effect

Question 20

what are the uses of alpha

Answer 20

smoke detectors- americium 241

Question 21

what are the uses of beta

Answer 21

carbon-14 dating
iodine-131 measures iodine uptake by thyroid

Question 22

what are the uses of gamma

Answer 22

cobalt-60 used to sterilise medical equipment

Question 23

is alpha dangerous

Answer 23

only of inhaled or ingested will it cause cancer as it cannot penetrate skin

Question 24

is beta dangerous

Answer 24

yes. it can be absorbed by the skin and can cause sunburn but it is most dangerous when ingested or inhaled

Question 25

is gamma dangerous

Answer 25

yes. can penetrate skin easily and will cause cancer

Question 26

nuclear reaction

Answer 26

process that alters the composition, structure, or energy of an atomic nucleus

Question 27

give 3 differences between nuclear and chemical reactions

Answer 27

nuclear: involves changes to the nucleus a new element is formed no chemical bonds are formed or broken chemical: involves electrons not the nucleus no new elements are formed chemical bonds are broken and formed

Question 28

radioisotopes

Answer 28

a radioactive isotope ie carbon-14

Question 29

radiocarbon dating

Answer 29

a technique used to determine the age of an object containing carbon. it is based on the ratio of carbon-14 to carbon-12 in the object

Question 30

explain how radiocarbon dating works

Answer 30

the ratio of carbon 12 to carbon 14 is constant in living organisms when the organism dies no more carbon 14 is taken in and the carbon 14 already present in the organism decays. by measuring the ratio of carbon 12 to carbon 14 the age of the item can be calculated

Question 31

sources of background radiation

Answer 31

radon gas nuclear weapons testing and accidents like Chernobyl

Question 32

what equipment is used when investigating radiation

Answer 32

geiger muller tube rate meter sheet of paper 5mm sheet of aluminium alpha beta and gamma sources blocks of lead

Question 33

what is a geiger counter?

Answer 33

a geiger muller tube and a rate meter joined

Question 34

what is a geiger muller tube

Answer 34

a sensing instrument used to detect radiation

Question 35

what does a rate meter do?

Answer 35

counts the number of radioactive particles that enter the GM tube per second

Question 36

what is the procedure when investigating radiation

Answer 36

measure background level of radiation using a tongs and gloves hold alpha particle source close to the geiger muller tube note increase in radiation detected hold sheet of paper between alpha and GM tube number of radiation detected should drop repeat for beta (replacing sheet of paper with aluminium) and gamma (replacing sheet of paper for a block of lead)

Question 37

explain why it is impossible to change Pb into Au by a chemical reaction

Answer 37

chemical reactions involve electrons only and do not involve changes to the nucleus changing Pb into Au requires a nuclear reaction to alter the number of protons in the nucleus

Question 38

write the general formula for an alpha decay reaction

Answer 38

a 4 (a - 4) X------> He + (X-2) z 2 (z - 2)

Question 39

write the general formula for a beta decay reaction

Answer 39

a 0 (a ) X------> e- + (X+1) z -1 (z + 1)

Question 40

half life

Answer 40

time taken for half of the nuclei in a given radioactive sample to decay

Question 41

how do you calculate half life

Answer 41

1.divide how many years its asking for divided by the half life 2. divide the amount in the sample by 2 to the power of your answer in 1.