Atomic Structure Flashcards

1
Q

Define atom

A

The smallest part of an element that can exist.

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2
Q

All substances are made up of…?

A

atoms

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3
Q

The radius of an atom is …?

A

0.1 nm (1 x 1010 m)

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4
Q

The overall charge on an atom is…

A

zero/neutral

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5
Q

Define element

A

Contains only one type of atom

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6
Q

Substances found in the periodic table are…?

A

elements

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7
Q

Approximately how many elements are there?

A

100

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8
Q

Define isotope

A

An atom of the same element with different numbers of neutrons

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9
Q

Define radioactive decay

A

An unstable nucleus changes to become more stabe and gives out radiation

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10
Q

We cannot predict when a given atom will decay, this means that radioactive deacy is ….?

A

random

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11
Q

Define activity

A

Rate at which decay occurs

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12
Q

What are the units of activity?

A

Becquerels (Bq)

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13
Q

Define count rate

A

Number of decays recorded each second by a Geiger-Muller tube

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14
Q

Defne half life

A

The time taken for number of radioactive nuclei in a sample to halve OR time taken for count rate (or activity) from a sample to fall to half its initial value

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15
Q

Define contamination

A

The unwanted presence of materials containing radioactive atoms

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16
Q

Define irradiation

A

When an object is exposed to radiation

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17
Q

Does an irradiatied object become radioactive itself?

A

no

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18
Q

The process of radiation removing electrons from atoms to form ions is called…?

A

ionisation

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19
Q

If ionisation happens in DNA it can cause ___________ which may result in ____________

A

mutations, cancer

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20
Q

Define peer review

A

Checking of scientific results by other scientific experts

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21
Q

Define mass number

A

The total number of protons and neutrons in an atom

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22
Q

Define atomic number

A

The number of protons in an atom (number of electrons is the same in a neutral atom)

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23
Q

Electrons in atoms are located in ___________

A

energy levels

24
Q

Absorption of radiation by an atom may result in ____________ moving to a ________________ energy level

A

electrons, higher

25
Q

Emission of radiation from an atom may lead to _____________ moving to a ______________ energy level

A

electrons, lower

26
Q

Who came up with the Plumb Pudding model of the atom

A

J J Thompson

27
Q

Describe the Plumb Pudding model of the atom

A

A ball of positive charge with negative electrons embedded in it

28
Q

Was the Plumb Pudding model correct?

A

no

29
Q

What experiment did Rutherford do?

A

Alpha particle scattering

30
Q

What did Rutherford’s experiment reveal?

A

Atoms have a central area of positive charge with electrons surrounding it

31
Q

Who discovered that electrons are located in energy levels?

A

Niels Bohr

32
Q

What did Jame Chadwick discover about the atom?

A

That the nucleus contains neutrons as well as protons

33
Q

What did John Dalton contribute to our understanding of atomic theory?

A

Matter is made up of descrete, spherical particles, known as atoms

34
Q

Name the three subatomic particles

A

proton, neutron, electron

35
Q

Which particles are located in the atoms nucleus

A

protons, neutrons

36
Q

What is the charge of each subatomic particle?

A

proton +1, neutron 0, electron -1

37
Q

What is the mass of each subatomic particle?

A

proton 1, neutron 1, elecrton ≈ 0

38
Q

Name the three types of radiation

A

alpha, beta and gamma

39
Q

What is an alpha particle?

A

two protons and two neutrons

40
Q

What is a beta particle?

A

an electron

41
Q

What is gamma radiation?

A

electromagnetic wave (NOT a particle)

42
Q

What is the range of alpha radiation in air?

A

short - 5 cm in air

43
Q

What is the range of gamma radiation in air?

A

unlimited in air

44
Q

What’s the range of beta radiation in air?

A

medium - about 1 m

45
Q

What will absorb (stop) alpha radiation?

A

paper/skin

46
Q

What will absorb (stop) beta radiation?

A

about 5 mm aluminium

47
Q

What will absorb (stop) gamma radiation?

A

several centimetres of lead

48
Q

What is the ionising power of alpha radiation?

A

very high

49
Q

What is the ionising power of beta radiation?

A

medium

50
Q

What is the ionising power of gamma radiation?

A

low

51
Q

What is meant by the ionising power of radiation?

A

how likely it is to ionise atoms which it comes into contact with

52
Q

How does alpha decay alter the mass number of the parent nucleus?

A

decreases by 4

53
Q

How does alpha decay alter the atomic number of the parent nucleus?

A

decreases by 2

54
Q

How does beta decay alter the mass number of the parent nucleus?

A

stays the same

55
Q

How does beta decay alter the atomic number of the parent nucleus?

A

increases by 1

56
Q

How does gamma radiation alter the mass and atomic number of the parent nucleus

A

unchanged (energy is released as the particles in the nucleus reorganise to a lower energy arrangement)