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A-Level Chemistry [OCR B] (updated: > Elements Of Life > Flashcards

Elements Of Life Flashcards

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1
Q

[EL1] What is the atomic number?

A

The number of protons present in the nucleus of an atom.

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2
Q

[EL1] What is the mass number?

A

The total number of nucleons (protons and neutrons_ present in the nucleus of an atom.

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3
Q

[EL1] What is the relative atomic mass?

A

The mean mass of an atom of an element compared to 1/12th the mass of an atom of carbon-12.

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4
Q

[EL1] What is the relative molecular mass?

A

The mean mass of a molecule compared to 1/12th the mass of an atom of carbon-12.

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5
Q

[EL1] What is relative formula mass?

A

The sum of the mean masses of all atoms in the formula of a compound compared to 1/12th the mass of an atom of carbon-12.

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6
Q

[EL1] What is the relative isotopic mass?

A

The mass of an atom isotope compared with 1/12th the mass of an atom of carbon-12.

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7
Q

[EL1] What is the mole?

A

The amount of substance containing as many particles as there are atoms in 12g of carbon-12.

1 mole = 6.02 x 10²³ items (Avagadro constant).

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8
Q

[EL1] What is an ionic equation?

A

An equation in which only the non-spectating ions are shown.

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9
Q

[EL1] How is percentage yield calculated?

A

%yield = ( actual yield / expected yield ) x 100

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10
Q

[EL1] How is percentage composition by mass calculated?

A

%composition = ( mass of desired substance / mass of mixture ) x 100

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11
Q

[EL1] How is a standard solution prepared from a concentrated solution?

A
  • A certain volume of the concentrated solution is added to a volumetric flask in order to get the desired final volume.
  • Distilled water is added to the volumetric flask up to the line on its neck.
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12
Q

[EL2] What are the shapes of s and p orbitals?

A

s: Sphericle
p: Like two balloons attached at the knot (repeated in x, y and z-axis)
https: //cdn.britannica.com/54/3254-050-6DB9F924/Electron-orbitals-orbital-atoms-p.jpg

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13
Q

[EL2] What are orbitals?

A
  • Regions in the space around an atom where electrons are most likely to be found.
  • They can contain a maximum of two electrons.
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14
Q

[EL2] How are electrons arranged in orbitals?

A
  • Electrons fill from the lowest energy orbital first.
    (e. g. they will not fill the fourth shell first)
  • Electrons will prefer (not as if they have a conscience to prefer but…) to occupy orbitals by themselves, and will only pair with other electrons if no other lower energy orbitals are available to fill.
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15
Q

[EL2] How are orbital filled on the energy level diagram?

A

Each box on the diagram represents one orbital and each arrow represents one electron.

The electrons spin at the same rate in either a clockwise (↑) or anticlockwise (↓) direction.

Electrons fill each of the 2p orbitals individually before pairing.

https://drive.google.com/file/d/1aB-kEytdxc_uPbMw8iMBgqyesorK63dI/view?usp=sharing

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16
Q

[EL2] Why does the 4s orbital fill before the 3d orbital?

A

The 4s orbital is of lower energy than the 3d orbital so it fills up first.

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17
Q

[EL2] What is the plum pudding model?

A

Charge is equally distributed around the atom.

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18
Q

[EL2] What did the Geiger-Marsden experiment show?

A

That the atom contained a very small, dense. positive nucleus.

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19
Q

[EL2] What is fusion?

A

When two lighter nuclei collide and combine to form a heavier nucleus, releasing energy.

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20
Q

[EL2] What are the conditions for fusion to happen?

A

A very high temperature and pressure.

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21
Q

[EL3] What is covalent bonding?

A
  • When a pair of electrons is shared between two atoms.
  • Covalent bonds are strong as there is a strong electrostatic attraction between these share electrons and the nuclei of the bonded atoms.
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22
Q

[EL3] Why do giant covalent lattices have a much grater melting point than simple covalent molecules?

A

The covalent bonds between the atoms in a giant covalent lattice are much stronger than the induced di-di interactions between the simple covalent molecule.

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23
Q

[EL3] Why are ionic substances only conductive when dissolved?

A
  • When ions are in a solid, they are unable to move so they cannot carry a charge.
  • Dissolving the solid causes the ions to be mobile so they are free to carry charge.
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24
Q

[EL3] Why do covalent and ionic lattices have high melting points?

A

Both lattices contain atoms that have multiple strong bonds around them, these bonds take a lot of (thermal) energy to break.

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25
Q

[EL3] What are the non-linear bond angle conditions?

A

104.5⁰

Two bonded pairs.

Two lone pairs.

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26
Q

[EL3] What are the trigonal planar bond angle and conditions?

A

120⁰

Three bond pairs.

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27
Q

[EL3] What are the trigonal pyramidal bond angle and conditions?

A

107⁰

Three bonded pairs.

One lone pair.

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28
Q

[EL3] What are the tetrahedral bond angle and conditions?

A

109.5⁰

Four bonded pairs.

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29
Q

[EL3] What are the octahedral bond angle and conditions?

A

90⁰

Six bonded pairs.

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30
Q

[EL3] How do different numbers of bonded and lone pairs produce different shapes in molecules?

A

Lone pairs repel more than bonded pairs.

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31
Q

[EL3] How does bonding occur in an ionic lattice?

A

The attraction between ions of different charges and the repulsion between ions of the same charge causes overall attraction in the lattice.

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32
Q

[EL4] What is first ionisation enthalpy?

A

The enthalpy change that occurs when one mole of electrons is removed from one mole of gaseous atoms.

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33
Q

[EL4] What does the group (column) number represent in the periodic table?

A

The number of electrons present in the outer shell of the atom.

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34
Q

[EL4] What does the period (row number) represent in the periodic table?

A

The number of electron shells in the atom.

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35
Q

[EL4] Why does first ionisation increase as we move across a period?

A
  • The number of protons in the nucleus increases which increases the nuclear charge and thus the nuclear force felt by outer electrons.
  • It, therefore, takes more energy to remove them.
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36
Q

[EL4] What is the formula of a nitrate ion?

A

NO₃⁻

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37
Q

[EL4] What is the formula of a sulphate ion?

A

SO₄²⁻

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38
Q

[EL4] What is the formula of a carbonate ion?

A

CO₃²⁻

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39
Q

[EL4] What is the formula of a hydroxide ion?

A

OH⁻

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40
Q

[EL4] What is the formula of an ammonium ion?

A

NH₄⁺

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41
Q

[EL4] What is the formula of an hydrogencarbonate ion?

A

HCO₃⁻

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42
Q

[EL4] What is the formula of a copper ion?

A

Cu²⁺

43
Q

[EL4] What is the formula of a zinc ion?

A

Zn²⁺

44
Q

[EL4] What is the formula of a lead ion?

A

Pb²⁺

45
Q

[EL4] What is the formula of an Iron(II) ion?

A

Fe²⁺

46
Q

[EL4] What is the formula of an Iron(III) ion?

A

Fe³⁺

47
Q

[EL4] Why does first ionisation energy decrease down a group?

A
  • The number of shells in the atom decreases, which increases the shielding of outer electrons from the nucleus.
  • The nuclear radius also increases.
  • Both of these factors mean that the attractive nuclear force felt by the electron is smaller, so it takes less energy to remove outer electrons.
48
Q

[EL4] How do the charge densities of group 2 ions affect the thermal stability of their carbonates?

A

Smaller ions with the same charge have higher charge densities and distort the carbonate ion, so that the compound will decompose at a lower temperature.

49
Q

[EL4] How can we test Fe²⁺ ions?

A

Add OH⁻ ions.

The green solution will form a green precipitate.

50
Q

[EL4] How can we test Fe³⁺ ions?

A

Add OH⁻ ions.

The yellow solution will form a orange precipitate.

51
Q

[EL4] How can we test Cu²⁺ ions?

A

Add OH⁻ ions.

The light blue solution will form a blue precipitate.

52
Q

[EL4] How can we test NH₄⁺ ions?

A

Add NaOH(aq) to a boiling tube containing the NH₄⁺ ions.

Heat the boiling tube.

Any vapours given off by the tube will turn damp red litmus paper blue if NH₄⁺ ions are present.

53
Q

[EL4] How can we test Al³⁺ ions?

A

Add OH⁻ ions.

The colourless solution will form a white precipitate.

54
Q

[EL4] How can we test Cl⁻ ions?

A

Add a few drops of HNO₃.

Shake the test tube.

Add a few drops of AgNO₃.

A white precipitate should form.

55
Q

[EL4] How can we test Br⁻ ions?

A

Add a few drops of HNO₃.

Shake the test tube.

Add a few drops of AgNO₃.

A cream precipitate should form.

56
Q

[EL4] How can we test I⁻ ions?

A

Add a few drops of HNO₃.

Shake the test tube.

Add a few drops of AgNO₃.

A yellow precipitate should form.

57
Q

[EL4] How can we test SO₄²⁻ ions?

A

Add Ba²⁺ ions.

A white precipitate should form.

58
Q

[EL4] How can we test CO₃²⁻ ions?

A

Add dilute HNO₃.

If effervescence occurs (it fizzes) then CO₃²⁻ ions are present.

59
Q

[EL4] How can we test for Li⁺, Na⁺, K⁺, and Ca⁺ ions?

A

Evaporate the water from the sample.

Moisten a test wire and colect the solid residue from the evaporating dish.

Pass this residue into a bunsen burner and record the colour of the flame.

60
Q

[EL4] Which ions show which colours in the metal ion flame test?

A

Na⁺ = Orange

Ca⁺ = Brick red

Li⁺ = Red

K⁺ = Lilac

Ba²⁺ = Green

Cu²⁺ = Blue-Green

61
Q

[EL4] How can we test for Pb²⁺ ions?

A

Add OH⁻ ions.

a white precipitate will form.

Upon adding excess OH⁻ ions, the precipitate will dissolve.

62
Q

[EL5] What is an acid?

A

A substance that releases H⁺ ions in solution.

63
Q

[EL5] What is an alkali?

A

A substance that releases OH⁻ ions in solution.

64
Q

[EL5] What is a base?

A

A soluble alkali.

65
Q

[EL5] What is neutralisation?

A

neutralisation is when the proton on an acid molecule is replaced by a metal ion (or ammonia), forming a salt and water.

66
Q

[EL5] How do group 2 oxides react with water?

A

(M = Group 2 metal)

MO + H₂O → M(OH)₂

Group 2 oxides are therefore basic as they release OH⁻ ions when dissolved.

67
Q

[EL5] How do group 2 hydroxides react with hydrochloric acid?

A

(M = Group 2 metal)

M(OH)₂ + 2HCl → MCl₂ + 2H₂O

Group 2 oxides are therefore basic as they release OH⁻ ions when dissolved.

68
Q

[EL6] Place the following in order of decreasing frequency: Gamma, X-Rays, Infrared, Microwaves.

A
  1. Gamma
  2. X-Rats
  3. Infrared
  4. Microwaves
69
Q

[EL6] What is the relationship between the energy emitted and the frequency of the line in the spectra?

A

E = hv

E: Energy (J)

h: Planck’s constant (6.63 x 10⁻³⁴ J/s)
v: Frequacy (s⁻¹)

70
Q

[EL6] What is the relationship between the wavelength of electromagnetic waves and their frequency?

A

c = vλ

c: Speed of Light (3.00 x 10⁸ ms⁻¹)
v: Frequency (s⁻¹)
λ: wavelength (m)

71
Q

[EL6] Which ions show which colours in the flame test?

A

Na⁺ = Orange

Ca⁺ = Brick red

Li⁺ = Red

K⁺ = Lilac

Ba²⁺ = Green

Cu²⁺ = Blue-Green

72
Q

What is the quantisation of energy?

A

The idea that, at the sub-atomic level, energy exists in specific packets called ‘quanta’.

73
Q

[EL7] How do you use a mass spectrum to deduce the relative atomic mass of a sample of an element?

A

SUM of (rel.abundance x m/z) / SUM of (rel.abundance)

74
Q

[EL2] Describe an absorption spectroscopy.

A
  • An atom is excited with energy.
  • This excites its electrons to a higher energy level.
  • If an arrow goes off the spectroscope graph, the atom has ionised.
  • The spectroscope will show black lines on a gradient background.
75
Q

[EL2] Describe an emission spectroscopy.

A
  • An excited electron falls from a higher energy level to a lower energy level.
  • Energy is quantised and os equal to E=hv
  • The spectroscope will show coloured lines on a black background.
76
Q

[EL2] Why do specific elements have specific colours of light?

A
  • Each energy level is unique to each element.
  • Therefore the wavelength emitted is unique.
  • This means each element will give off its own colour of light.
77
Q

[EL1] What is the relative mass of an electron?

A

11/20000 (0.00055)

78
Q

[EL1] What is a fusion reaction?

A

Lighter nuclei joining to give heavier nuclei, this is how certain elements are formed.

79
Q

[EL1] What conditions are necessary for a fusion reaction?

A

High temperature and pressure.

80
Q

[EL1] How do you use a mass spectra to calculate relative atomic mass?

A

SUM of (m/z x intensity) / SUM of intensity

81
Q

[EL1] Show nuclear fusion to create Helium-3.

A

¹H + ²H → ³He + γ

γ: indicates the release of energy when the fusion reaction occurs.

82
Q

[EL1] A ⁷Li nucleus absorbs a colliding proton and then disintegrates into two identical fragments. Show this as nuclear equations.

A

⁷Li + ¹H → ⁸Be
⁸Be → 2⁴He

∴ ⁷Li + ¹H → 2⁴He

83
Q

[EL2] List the EM spectrum in order of increasing frequency.

A 
Radio
Microwave
Infrared
Visible
Ultraviolet
X-rays
γ-rays
84
Q

[EL2] List the EM spectrum in order of increasing energy.

A 
Radio
Microwave
Infrared
Visible
Ultraviolet
X-rays
γ-rays
85
Q

[EL2] List the EM spectrum in order of increasing wavelength.

A 
γ-rays
X-rays
Ultraviolet
Visible
Infrared
Microwave
Radio
86
Q

[EL2] Link frequency, wavelenth and the speed of light quantitively.

A

c = λ v

87
Q

[EL2] Link frequency, Planks constant and the energy of a photon quantitively.

A

ΔE = h v

88
Q

[EL3] What is the maximum number of electrons in different sub-shells?

A

s: 2
p: 6
d: 10
f: 14

89
Q

[EL3] How many s-orbitals do s-sub-shells have?

A

one

90
Q

[EL3] How many p-orbitals do p-sub-shells have?

A

three

91
Q

[EL3] How many d-orbitals do d-sub-shells have?

A

five

92
Q

[EL3] How many f-orbitals do f-sub-shells have?

A

seven

93
Q

[EL3] What four pieces of info are needed when describing an electron:

A
  • The electron shell it’s in
  • It’s sub-shell
  • It’s orbital within the sub-shell
  • It’s spin
94
Q

[EL3] What is the electron configuration of Chromium? Why is this different?

A

1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵ 4s¹

As well as gaining an electron on its 3d orbital, it also moves one from its 4s to it.

95
Q

[EL3] What is the electron configuration of Copper? Why is this different?

A

1s² 2s² 2p⁶ 3s² 3p⁶ 3d¹⁰ 4s¹

As well as gaining an electron on its 3d orbital, it also moves one from its 4s to it.

96
Q

[EL4] What is the periodic table?

A

A list of elements in order of atomic number that groups elements together according to their properties

97
Q

[EL4] What is periodicity?

A

The occurrence of periodic patterns.

98
Q

[EL4] What is the trend in melting and boiling point in period 3?

A

Both the melting and Boiling points initially increase as you go across the period, and then fall dramatically from silicon, Si, to phosphorus.

This is similar in other periods.

99
Q

[EL4] What do the trends in melting and boiling point in period 3 mean?

A

Bonds between the particles in phosphorus must be much weaker and easier to overcome than those between the particle of silicon.

This is similar in other periods.

100
Q

[EL5] What is a dative covalent bond?

How is this show in a dot and cross?

A

A bond where both bonding electrons come from the same atom.

An arrow pointing away from the donating atom.

101
Q

[EL6] Relate Moles, mass and Mr.

A

Moles = mass(g) / Mr (g mol⁻¹)

102
Q

[EL6] What are the empirical formulae for these substances:

C₂H₄
C₆H₆
C₄H₁₀
P₄O₁₀
O₂
Br₂
A 
CH₂
CH
C₂H₅
P₂O₅
O
Br
103
Q

[EL8] What is the trend reactivity of s-block elements down and across the periodic table?

A

Down a group = more reactive

Across a period = less reactive

A-Level Chemistry [OCR B] (updated: (5 decks)

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