atomic structure Flashcards

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1
Q

radius of an atom

A

1 x 10 - 10 metres

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2
Q

how does the radius of the nucleus compare to that of an atom

A

at least 10 000 times smaller

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3
Q

where is most of the mass in an atom concentrated?

A

the nucleus

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4
Q

how are electrons arranged in atoms

A

energy levels

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5
Q

what happens when an electron absorbs electromagnetic radiation

A

moves to a higher energy level

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6
Q

what happens when an electron emits electromagnetic radiation

A

moves to a lower energy level

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7
Q

what is the mass of a proton

A

1

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8
Q

what is the mass of a neutron

A

1

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9
Q

what is the mass of an electron

A

1/2000 (nearly 0)

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10
Q

what is the charge of a proton

A

1

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11
Q

what is the charge of an electron

A

-1

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12
Q

what is the charge of a neutron

A

0

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13
Q

where are protons found

A

in the nucleus of an atom

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14
Q

where are neutrons found

A

in the nucleus of the atom

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15
Q

where are electrons found

A

in energy levels orbiting the nucleus

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16
Q

what is the atomic number

A

the number of protons

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17
Q

what is the mass number

A

the number of protons and neutrons

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18
Q

how do you find the number of neutrons in an atom

A

mass number - atomic number

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19
Q

why do atoms have no overall charge

A

they have the same number of protons and electrons

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20
Q

how do ions get charged

A

by an atom gaining or loosing electrons

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21
Q

how can atoms turn into positive ions?

A

lose one or more outer electrons

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22
Q

what is an isotope?

A

atoms of the same element with the same number of protons but different number of neutrons

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23
Q

what can lead to a scientific model being replaced

A

new experimental evidence

24
Q

before the electron was discovered atoms were thought to be…

A

tiny indivisible spheres

25
Q

what discovery led to the plum pudding model

A

the electron

26
Q

what was the plum pudding model?

A

a ball of positive charge with negative electrons embedded in it

27
Q

draw the plum pudding model

A

google it

28
Q

what were the results of the alpha scattering experiment?

A

most particles passed straight through, some were deflected by small angles, a few deflected by large angles

29
Q

what conclusion was made from the alpha scattering experiment

A

the mass of an atom was concentrated in the centre (nucleus) and that the nucleus was charged

30
Q

what improvements did neils bohr suggest

A

electrons orbit at specific distances

31
Q

what was the first subatomic part of the nucleus to be discovered

A

the proton

32
Q

what did james chadwick discover

A

the neutron

33
Q

what is radioactive decay

A

unstable nuclei give out radiation as they change to become different elements that are more stable

34
Q

can we predict when an atom will decay?

A

no, its a random process

35
Q

what is activity

A

the rate at which a source decays

36
Q

what are the units for radioactivity

A

becquerel (Bq)

37
Q

what are the different types of radiation

A

alpha particle, beta particle, gamma ray, neutron

38
Q

what is an alpha particle

A

2 neutrons 2 protons

39
Q

what is a beta particle

A

high speed electron ejected from the nucleus as a neutron turns into a proton

40
Q

how might an alpha particle be represented in a nuclear equation

A

4
He
2

41
Q

how might a beta particle be represented in a nuclear equation

A

0
e
-1

42
Q

what is a gamma ray

A

electromagnetic radiation from the nucleus

43
Q

what is ionising radiation

A

removes electrons from atoms

44
Q

which type of radiation is the most ionising

A

alpha

45
Q

which type of radiation is the least ionising

A

gamma

46
Q

which type of radiation is the most penetrating

A

gamma

47
Q

which type of radiation is least penetrating

A

alpha

48
Q

what is a half life

A

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

49
Q

what is radioactive contamination

A

radioactive atoms on other materials

50
Q

what is irradiation

A

exposing an object to nuclear radiation

51
Q

what are the natural sources of background information

A

rocks and cosmic rays from space

52
Q

what are the man made sources of background radiation

A

nuclear weapons testing, nuclear accidents

53
Q

what are the uses of radiation in medicine

A

exploration of internal organs, control or destruction of unwanted tissues

54
Q

what is nuclear fission

A

the splitting of a large and unstable nucleus

55
Q

what is usually needed for nuclear fission

A

the unstable nucleus absorbs a neutron

56
Q
A