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Atomic structure! Flashcards

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1
Q

What are the 3 subatomic particles?

A

Proton, neutron, electron

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2
Q

What are the charges and location of protons and electrons?

A

Proton: +1, in the nucleus
Electron: -1, in orbitals around the nucleus

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3
Q

What is the role of neutrons in the nucleus?

A

They add mass and help stabilise the nucleus

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4
Q

What is an ion?

A

An atom or molecule with a charge due to losing or gaining electrons

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5
Q

What is a cation?

A

A positively charged ion formed by losing electrons

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6
Q

What is an anion?

A

A negatively charged ion formed by gaining electrons

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7
Q

What is an electrolyte?

A

A substance that conducts electricity in solution by releasing ions

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8
Q

What is the maximum number of electrons in an S orbital?

A

2

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9
Q

What is the order of orbital filling?

A

1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f……

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10
Q

What are the 4 quantum numbers?

A

n (shell)
I (subshell)
m (orbital orientation)
s (spin)

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11
Q

Name the state symbols

A

aq (Aqueous)
s (Solid)
g (Gas)
l (Liquid)

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12
Q

What is the formula for concentration in mol/dm³?

A

C = n/V

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13
Q

What is the formula for moles using mass?

A

n = m/Mr

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14
Q

How many particles are in one mole? (Avogadro’s number)

A

6.022 × 10²³

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15
Q

What is the molar volume of gas at room temp?

A

24 dm³/mol (at 20°C and 1 atm)

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16
Q

What is the formula to convert g/dm³ to mol/dm³?

A

C = m/(Mr x V)

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17
Q

What is ionisation energy?

A

The energy needed to remove one mole of electrons from one mole of gaseous atoms

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18
Q

Why is the second ionisation energy higher than the first?

A

Because it’s harder to remove an electron from a positively charged ion

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19
Q

What factors affect ionisation energy?

A

Atomic radius, nuclear charge, shielding, orbital stability

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20
Q

How does atomic radius affect ionisation energy?

A

Larger atoms = lower ionisation energy (electrons are further away)

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21
Q

How does nuclear charge affect ionisation energy?

A

More protons = higher attraction = higher ionisation energy

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22
Q

How does shielding affect ionisation energy?

A

More inner shells = more shielding = lower ionisation energy

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23
Q

Why is it easier to remove paired electrons?

A

They repel each other slightly

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24
Q

What is relative atomic mass (Ar)?

A

The average mass of isotopes compared to 1/12 of carbon-12

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25
What is the relative molecular mass (Mr)?
The sum of Ar values in a molecule
26
What is radioactivity?
Spontaneous emission of radiation from an unstable nucleus
27
What are the three types of radiation?
Alpha, Beta, Gamma
28
What is alpha radiation?
2 protons + 2 neutrons (He nucleus) (low penetration)
29
What is beta radiation?
High-speed electron from nucleus. (medium penetration)
30
What is gamma radiation?
High-energy wave, no mass or charge. (high penetration)
31
What is a radioactive isotope?
An unstable isotope that emits radiation to become stable
32
What is a half life?
The time required for a substance to reduce to half of its initial value
33
How do you calculate decay?
N = N₀ × (½)ⁿ, where n = number of half-lives
34
What is radioactivity?
Radioactivity is the spontaneous emission of particles or electromagnetic radiation from an unstable atomic nucleus.
35
What factors influence the stability of an atomic nucleus?
The neutron/proton (n/p) ratio, total nuclear charge, and whether the nucleus is light or heavy.
36
How does the n/p ratio affect nuclear stability?
Light nuclei are more stable with n/p ≈ 1. Heavy nuclei require higher n/p ratios for stability. An odd n/p ratio often leads to instability.
37
What are the main types of radioactive decay and their associated radiations?
Alpha decay (α): emission of helium nucleus; Beta decay (β): neutron/proton conversion; Gamma radiation (γ): emission of high-energy photons; Positron emission (β⁺): for light nuclei with n/p < 1; Electron capture (EC): proton turns into neutron by capturing orbital electron.
38
What occurs during electron capture?
An inner-shell electron is captured by the nucleus, converting a proton into a neutron and emitting a neutrino (νₑ) and an X-ray.
39
What are the modern and old units for measuring radiation activity?
New: Becquerel (Bq) = 1 disintegration/sec. Old: Curie (Ci) = 3.7 × 10¹⁰ disintegrations/sec.
40
What are the modern and old units for absorbed radiation dose?
New: Gray (Gy) = 1 J/kg. Old: rad. 1 rad = 0.01 Gy.
41
What are the modern and old units for biological damage from radiation?
New: Sievert (Sv). Old: rem. 1 rem = 0.01 Sv.
42
What are the radiation weighting factors used in Sievert calculations?
1 for β, γ, and X-rays; 10 for high-energy protons and neutrons; 20 for α-radiation.
43
What is the general form of the radioactive decay equation?
ln[N] = ln[N₀] - λt. ## Footnote Example: ln[¹³¹I] = 2.9957 - 0.0866·t
44
What is half-life?
The time it takes for half of the radioactive nuclei in a sample to decay.
45
How are natural radioisotopes formed?
They originate from long-lived isotopes and can be produced by cosmic ray interactions.
46
How are artificial radioisotopes produced?
By transmutation: bombarding stable isotopes with α-particles, protons, or neutrons.
47
What are some applications of radioactive isotopes?
Carbon dating, radioimmunoassay, medical imaging and treatment, nuclear energy generation.
48
What’s the difference between nuclear fission and fusion?
Fission splits heavy nuclei to release energy. Fusion combines light nuclei to form a heavier nucleus, releasing energy.
49
Why are heavy nuclei typically unstable?
Heavy nuclei have many protons, which create strong electrostatic repulsion. ## Footnote More neutrons are needed to add nuclear binding through the strong force.
50
What happens if the neutron-to-proton (n/p) ratio isn't high enough?
The nucleus becomes unstable and undergoes radioactive decay.
51
How do you find moles?
Moles = mass/molar mass
52
Where does the periodic table get more elctronegative?
As you go right and up, but also hydrogen is very electronegative
53
How much of the atoms total mass does the nucleus contain?
99.9%
54
What is the ionisation energy?
Energy required to remove an electron from a gaseous atom
55
What is the electron affinity?
Energy required to add an electron to a gaseous atom
56
What is exothermic electron addition?
When an atom or molecule gains an electron and releases energy, the process is exothermic. This means the resulting species is more stable with the extra electron
57
What does an atom having endothermic electron affinity mean?
The atom or molecule does not easily accept an extra electron. The resulting anion is less stable or not energetically favorable. The enthalpy change (ΔH) is positive — you have to put in energy to make it happen
58
What group is the most exothermic?
Halogens - group 7 They really want an electron
59
Define 1st ionisation energy
The first ionisation energy is the energy needed to remove the outermost electron from a neutral gaseous atom
60
What is the general trend in ionisation energies?
Increases from 1st, 2nd, 3rd etc.
61
Which groups have a low or 0 endothermic electron affinity?
Noble gases, metals They do not want the electron
62
Weirdly, what comes after 3p?
4s
63
What happens in a nuclear reactioin?
Changes occur to the fundamental protons or neutrons, changing the atoms identity - nuclear decay, gives off some form of radiation
64
What is an alpha particle?
Essentially helium - 2 protons and 2 neutrons
65
What are the 4 quantum numbers applied to electrons and what do they tell us?
66
Define stable isotopes
Atoms with the same number of protons but different numbers of neutrons that do not decay over time.
67
What are radioactive isotopes?
These do decay, emitting radiation in the process. Their nuclei are unstable due to an imbalance in the neutron-to-proton ratio (n/p)
68
What are light nuclei?
Atoms with a low atomic number, typically less than or equal to 20
69
What are heavy nuclei?
Atoms with a high atomic number, typically more than or equal to 20
70
Why are heavy nuclei harder to stabilise?
More protons = more repulsion → need extra neutrons to dilute this charge and stabilize the nucleus
71
What kind of radiation do heavy nuclei usually emit?
alpha decay
72
What kind of radiation is normally emitted by light nuclei with low n/p ratios?
Beta
73
What is beta- radiation?
β⁻ Decay: A neutron turns into a proton, emitting an electron (β⁻) and an antineutrino (ν̅ₑ)
74
What is beta+ radiation?
β⁺ Decay (positron emission): A proton turns into a neutron, emitting a positron (β⁺) and a neutrino (νₑ)
75
What is gamma radiation and what is it blocked by?
A nucleus in an excited state releases energy as a γ-ray No mass or charge – pure energy Very penetrating (only blocked by thick lead/concrete)
76
Describe electron capture (form of radiation)
A proton-rich nucleus captures an inner electron. Converts a proton to a neutron, releasing an X-ray and a neutrino (νₑ). Competes with β⁺ decay in some isotopes
77
Name a typical source of alpha radiation
Radium-226
78
Name a typical source of beta radiation
Carbon-14
79
What is the new unit used to measure radiation activity?
becquerel 1disintegrations/s = 1 Bq
80
What is the new unit used to measure absorbed radiation?
Gray 1 J/kg = 1 Gy
81
What is the new unit used to measure biological damage by radiation? What are the typical measurements for each type of radiation?
Sievert 1 Gy x factor = 1 Sv 1 for β, γ and X-rays, 10 for high-energy protons and neutrons, 20 for α- radiation
82
Define half life
The time taken for half the radioactive nuclei in a sample to decay
83
What is a radioisotope?
A radioisotope is an isotope of an element that has an unstable nucleus and undergoes radioactive decay, emitting radiation in the form of alpha (α), beta (β), or gamma (γ) rays
84
How are radioisotopes made artifically?
Created by bombarding stable isotopes with: Neutrons Protons Alpha particles This process is called nuclear transmutation
85
What 2 methods are natural radioisotopes produced by?
Primordial formation Cosmic ray interactions

Biochemistry (14 decks)

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