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gcse revision! > atomic structure > Flashcards

atomic structure Flashcards

1
Q

what did john dalton say?

A

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

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2
Q

what did JJ Thomson discover?

A

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

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3
Q

what did rutherford discover?

A

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.

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4
Q

what did neil bohrs say?

A

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

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5
Q

what did James Chadwick prove?

A

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

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6
Q

what makes up most mass of an atom?

A

the nucleus

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7
Q

what does number of protons =? (atomic number)

A

number of electrons

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8
Q

what do unstable isotopes tend to do?

A

decay and realise radiation trying to become more stable

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9
Q

what are alpha particles?

A

helium nuclei.

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10
Q

whats in alpha particles?

A

2 neutrons and 2 protons

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11
Q

explain alpha particles?

A

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

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12
Q

what are beta particles?

A

high speed electrons

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13
Q

what in an beta particles?

A

no mass, charge of -1

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14
Q

explain beta particles?

A

moderately ionising
penetrate moderately
absorbed by sheet of aluminium

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15
Q

what happens everytime a beta particle is emitted?

A

a neutron in the nucleus is turned into a proton

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16
Q

what are gamma rays?

A

EM waves with short wavelengths

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17
Q

what are gamma rays made up of?

A

electromagnetic radiation released by the nucleus

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18
Q

explain gamma rays?

A

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

19
Q

what happens when an alpha particle is emitted?

A

atomic number reduces by 2
mass number reduces by 4

20
Q

what happens when a beta particle is emitted?

A

increase atomic number by 1
mass stays the same

21
Q

what happens when a gamma ray is emitted?

A

no chance in atomic mass or atomic number

22
Q

what can radiation be measured with?

A

geiger-muller tube and counter.

23
Q

what can half-life be used to find?

A

rate that a source decays

24
Q

whats the problem with trying to measure decay?

A

activity never reaches 0

25
Q

what does a short half life mean?

A

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

26
Q

what does a long half life mean?

A

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

27
Q

what does radiation dose tell us?

A

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

28
Q

where can background radiation be found?

A

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

29
Q

what does irradiated mean?

A

exposed to radiation.

30
Q

how to you reduce irradiation?

A

keeping sources in lead lined boxes

31
Q

what does contaminated mean?

A

unwanted radioactive atoms getting onto an object

32
Q

what should you use when handling sources?

A

tongs and gloves, protective suits.

33
Q

what sources are most dangerous outside the body?

A

beta and gamma

34
Q

why are gamma and beta rays dangerous?

A

they can penetrate body to get to delicate organs

35
Q

whats most dangerous inside the body?

A

alpha, most ionising.

36
Q

what are risks of radiation?

A

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

37
Q

how are gamma rays used in medical tracers?

A

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

38
Q

what happens during radiotherapy? (treating cancer with radiation)

A

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

39
Q

risks of using radioactive materials?

A

can cause cancer

40
Q

benefits of using radioactive materials?

A

tracers can diagnose life-threatening conditions, can remove cancer

41
Q

what happens during nuclear fission?

A

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.

42
Q

what do control rods do?

A

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

43
Q

what is nuclear fusion?

A

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

gcse revision! (50 decks)

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