atomic structure

Question 1

what did john dalton say?

Answer 1

matter was made of tiny spheres, each element made up of a different type of atom

Question 2

what did JJ Thomson discover?

Answer 2

electrons that could be removed from atoms, atoms were spheres of positive charge with tiny negative electrons. plum pudding model.

Question 3

what did rutherford discover?

Answer 3

gold foil experiment with alpha particles, most of mass was concentrated at centre in a nucleus, that was positively charged, rest of atom was empty space.

Question 4

what did neil bohrs say?

Answer 4

electrons orbiting nucleus do it at a certain distance called energy levels.

Question 5

what did James Chadwick prove?

Answer 5

existance of the neutron, explained imbalance between atomic and mass number.

Question 6

what makes up most mass of an atom?

Answer 6

the nucleus

Question 7

what does number of protons =? (atomic number)

Answer 7

number of electrons

Question 8

what do unstable isotopes tend to do?

Answer 8

decay and realise radiation trying to become more stable

Question 9

what are alpha particles?

Answer 9

helium nuclei.

Question 10

whats in alpha particles?

Answer 10

2 neutrons and 2 protons

Question 11

explain alpha particles?

Answer 11

dont penetrate very far, stopped quickly, absorbed by shet of paper, strongly ionising.

Question 12

what are beta particles?

Answer 12

high speed electrons

Question 13

what in an beta particles?

Answer 13

no mass, charge of -1

Question 14

explain beta particles?

Answer 14

moderately ionising
penetrate moderately
absorbed by sheet of aluminium

Question 15

what happens everytime a beta particle is emitted?

Answer 15

a neutron in the nucleus is turned into a proton

Question 16

what are gamma rays?

Answer 16

EM waves with short wavelengths

Question 17

what are gamma rays made up of?

Answer 17

electromagnetic radiation released by the nucleus

Question 18

explain gamma rays?

Answer 18

penetrate far into materials, weakly ionising, absorbed by thick sheets of lead

Question 19

what happens when an alpha particle is emitted?

Answer 19

atomic number reduces by 2
mass number reduces by 4

Question 20

what happens when a beta particle is emitted?

Answer 20

increase atomic number by 1
mass stays the same

Question 21

what happens when a gamma ray is emitted?

Answer 21

no chance in atomic mass or atomic number

Question 22

what can radiation be measured with?

Answer 22

geiger-muller tube and counter.

Question 23

what can half-life be used to find?

Answer 23

rate that a source decays

Question 24

whats the problem with trying to measure decay?

Answer 24

activity never reaches 0

Question 25

what does a short half life mean?

Answer 25

they are dangerous as they release huge amounts of radiation at start.

Question 26

what does a long half life mean?

Answer 26

releases small amounts of radiation for a long time, (can be dangerous because nearby areas exposed to radiation for millions of years)

Question 27

what does radiation dose tell us?

Answer 27

risk of harm to the body tissues due to exposure to radiation

Question 28

where can background radiation be found?

Answer 28

in our food, in rocks, air, building materials.

Question 29

what does irradiated mean?

Answer 29

exposed to radiation.

Question 30

how to you reduce irradiation?

Answer 30

keeping sources in lead lined boxes

Question 31

what does contaminated mean?

Answer 31

unwanted radioactive atoms getting onto an object

Question 32

what should you use when handling sources?

Answer 32

tongs and gloves, protective suits.

Question 33

what sources are most dangerous outside the body?

Answer 33

beta and gamma

Question 34

why are gamma and beta rays dangerous?

Answer 34

they can penetrate body to get to delicate organs

Question 35

whats most dangerous inside the body?

Answer 35

alpha, most ionising.

Question 36

what are risks of radiation?

Answer 36

enter living cells and ionise atoms, damage tissue, cause cancer (mutation), kill cells

Question 37

how are gamma rays used in medical tracers?

Answer 37

pass through body without causing much ionisation, short half life so they disappear, swallowed or injected into people.

Question 38

what happens during radiotherapy? (treating cancer with radiation)

Answer 38

gamma rays directed at right dosage to kill cancer cells, damage done to normal cells that can cause sickness

Question 39

risks of using radioactive materials?

Answer 39

can cause cancer

Question 40

benefits of using radioactive materials?

Answer 40

tracers can diagnose life-threatening conditions, can remove cancer

Question 41

what happens during nuclear fission?

Answer 41

nucleus absorbs a neutron, atom splits to form 2 lighter elements, 2 or 3 neutrons released, if any are slow enough they could be absorbed by another nucleus so more fission occurs.

Question 42

what do control rods do?

Answer 42

absorb neutrons in reactors to slow down chain reaction and amount of energy released.

Question 43

what is nuclear fusion?

Answer 43

2 light nuclei collide and fuse, create larger heavier nucleus, releases lots of energy.