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

Elements Of Life Flashcards

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
[EL3] What are the non-linear bond angle conditions?
104.5⁰ Two bonded pairs. Two lone pairs.
26
[EL3] What are the trigonal planar bond angle and conditions?
120⁰ Three bond pairs.
27
[EL3] What are the trigonal pyramidal bond angle and conditions?
107⁰ Three bonded pairs. One lone pair.
28
[EL3] What are the tetrahedral bond angle and conditions?
109.5⁰ Four bonded pairs.
29
[EL3] What are the octahedral bond angle and conditions?
90⁰ Six bonded pairs.
30
[EL3] How do different numbers of bonded and lone pairs produce different shapes in molecules?
Lone pairs repel more than bonded pairs.
31
[EL3] How does bonding occur in an ionic lattice?
The attraction between ions of different charges and the repulsion between ions of the same charge causes overall attraction in the lattice.
32
[EL4] What is first ionisation enthalpy?
The enthalpy change that occurs when one mole of electrons is removed from one mole of gaseous atoms.
33
[EL4] What does the group (column) number represent in the periodic table?
The number of electrons present in the outer shell of the atom.
34
[EL4] What does the period (row number) represent in the periodic table?
The number of electron shells in the atom.
35
[EL4] Why does first ionisation increase as we move across a period?
- 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.
36
[EL4] What is the formula of a nitrate ion?
NO₃⁻
37
[EL4] What is the formula of a sulphate ion?
SO₄²⁻
38
[EL4] What is the formula of a carbonate ion?
CO₃²⁻
39
[EL4] What is the formula of a hydroxide ion?
OH⁻
40
[EL4] What is the formula of an ammonium ion?
NH₄⁺
41
[EL4] What is the formula of an hydrogencarbonate ion?
HCO₃⁻
42
[EL4] What is the formula of a copper ion?
Cu²⁺
43
[EL4] What is the formula of a zinc ion?
Zn²⁺
44
[EL4] What is the formula of a lead ion?
Pb²⁺
45
[EL4] What is the formula of an Iron(II) ion?
Fe²⁺
46
[EL4] What is the formula of an Iron(III) ion?
Fe³⁺
47
[EL4] Why does first ionisation energy decrease down a group?
- 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
[EL4] How do the charge densities of group 2 ions affect the thermal stability of their carbonates?
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
[EL4] How can we test Fe²⁺ ions?
Add OH⁻ ions. The green solution will form a green precipitate.
50
[EL4] How can we test Fe³⁺ ions?
Add OH⁻ ions. The yellow solution will form a orange precipitate.
51
[EL4] How can we test Cu²⁺ ions?
Add OH⁻ ions. The light blue solution will form a blue precipitate.
52
[EL4] How can we test NH₄⁺ ions?
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
[EL4] How can we test Al³⁺ ions?
Add OH⁻ ions. The colourless solution will form a white precipitate.
54
[EL4] How can we test Cl⁻ ions?
Add a few drops of HNO₃. Shake the test tube. Add a few drops of AgNO₃. A white precipitate should form.
55
[EL4] How can we test Br⁻ ions?
Add a few drops of HNO₃. Shake the test tube. Add a few drops of AgNO₃. A cream precipitate should form.
56
[EL4] How can we test I⁻ ions?
Add a few drops of HNO₃. Shake the test tube. Add a few drops of AgNO₃. A yellow precipitate should form.
57
[EL4] How can we test SO₄²⁻ ions?
Add Ba²⁺ ions. A white precipitate should form.
58
[EL4] How can we test CO₃²⁻ ions?
Add dilute HNO₃. If effervescence occurs (it fizzes) then CO₃²⁻ ions are present.
59
[EL4] How can we test for Li⁺, Na⁺, K⁺, and Ca⁺ ions?
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
[EL4] Which ions show which colours in the metal ion flame test?
Na⁺ = Orange Ca⁺ = Brick red Li⁺ = Red K⁺ = Lilac Ba²⁺ = Green Cu²⁺ = Blue-Green
61
[EL4] How can we test for Pb²⁺ ions?
Add OH⁻ ions. a white precipitate will form. Upon adding excess OH⁻ ions, the precipitate will dissolve.
62
[EL5] What is an acid?
A substance that releases H⁺ ions in solution.
63
[EL5] What is an alkali?
A substance that releases OH⁻ ions in solution.
64
[EL5] What is a base?
A soluble alkali.
65
[EL5] What is neutralisation?
neutralisation is when the proton on an acid molecule is replaced by a metal ion (or ammonia), forming a salt and water.
66
[EL5] How do group 2 oxides react with water?
(M = Group 2 metal) MO + H₂O → M(OH)₂ Group 2 oxides are therefore basic as they release OH⁻ ions when dissolved.
67
[EL5] How do group 2 hydroxides react with hydrochloric acid?
(M = Group 2 metal) M(OH)₂ + 2HCl → MCl₂ + 2H₂O Group 2 oxides are therefore basic as they release OH⁻ ions when dissolved.
68
[EL6] Place the following in order of decreasing frequency: Gamma, X-Rays, Infrared, Microwaves.
1. Gamma 2. X-Rats 3. Infrared 4. Microwaves
69
[EL6] What is the relationship between the energy emitted and the frequency of the line in the spectra?
E = hv E: Energy (J) h: Planck's constant (6.63 x 10⁻³⁴ J/s) v: Frequacy (s⁻¹)
70
[EL6] What is the relationship between the wavelength of electromagnetic waves and their frequency?
c = vλ c: Speed of Light (3.00 x 10⁸ ms⁻¹) v: Frequency (s⁻¹) λ: wavelength (m)
71
[EL6] Which ions show which colours in the flame test?
Na⁺ = Orange Ca⁺ = Brick red Li⁺ = Red K⁺ = Lilac Ba²⁺ = Green Cu²⁺ = Blue-Green
72
What is the quantisation of energy?
The idea that, at the sub-atomic level, energy exists in specific packets called 'quanta'.
73
[EL7] How do you use a mass spectrum to deduce the relative atomic mass of a sample of an element?
SUM of (rel.abundance x m/z) / SUM of (rel.abundance)
74
[EL2] Describe an absorption spectroscopy.
- 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
[EL2] Describe an emission spectroscopy.
- 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
[EL2] Why do specific elements have specific colours of light?
- 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
[EL1] What is the relative mass of an electron?
11/20000 (0.00055)
78
[EL1] What is a fusion reaction?
Lighter nuclei joining to give heavier nuclei, this is how certain elements are formed.
79
[EL1] What conditions are necessary for a fusion reaction?
High temperature and pressure.
80
[EL1] How do you use a mass spectra to calculate relative atomic mass?
SUM of (m/z x intensity) / SUM of intensity
81
[EL1] Show nuclear fusion to create Helium-3.
¹H + ²H → ³He + γ γ: indicates the release of energy when the fusion reaction occurs.
82
[EL1] A ⁷Li nucleus absorbs a colliding proton and then disintegrates into two identical fragments. Show this as nuclear equations.
⁷Li + ¹H → ⁸Be ⁸Be → 2⁴He ∴ ⁷Li + ¹H → 2⁴He
83
[EL2] List the EM spectrum in order of increasing frequency.
``` Radio Microwave Infrared Visible Ultraviolet X-rays γ-rays ```
84
[EL2] List the EM spectrum in order of increasing energy.
``` Radio Microwave Infrared Visible Ultraviolet X-rays γ-rays ```
85
[EL2] List the EM spectrum in order of increasing wavelength.
``` γ-rays X-rays Ultraviolet Visible Infrared Microwave Radio ```
86
[EL2] Link frequency, wavelenth and the speed of light quantitively.
c = λ v
87
[EL2] Link frequency, Planks constant and the energy of a photon quantitively.
ΔE = h v
88
[EL3] What is the maximum number of electrons in different sub-shells?
s: 2 p: 6 d: 10 f: 14
89
[EL3] How many s-orbitals do s-sub-shells have?
one
90
[EL3] How many p-orbitals do p-sub-shells have?
three
91
[EL3] How many d-orbitals do d-sub-shells have?
five
92
[EL3] How many f-orbitals do f-sub-shells have?
seven
93
[EL3] What four pieces of info are needed when describing an electron:
- The electron shell it's in - It's sub-shell - It's orbital within the sub-shell - It's spin
94
[EL3] What is the electron configuration of Chromium? Why is this different?
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
[EL3] What is the electron configuration of Copper? Why is this different?
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
[EL4] What is the periodic table?
A list of elements in order of atomic number that groups elements together according to their properties
97
[EL4] What is periodicity?
The occurrence of periodic patterns.
98
[EL4] What is the trend in melting and boiling point in period 3?
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
[EL4] What do the trends in melting and boiling point in period 3 mean?
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
[EL5] What is a dative covalent bond? | How is this show in a dot and cross?
A bond where both bonding electrons come from the same atom. An arrow pointing away from the donating atom.
101
[EL6] Relate Moles, mass and Mr.
Moles = mass(g) / Mr (g mol⁻¹)
102
[EL6] What are the empirical formulae for these substances: ``` C₂H₄ C₆H₆ C₄H₁₀ P₄O₁₀ O₂ Br₂ ```
``` CH₂ CH C₂H₅ P₂O₅ O Br ```
103
[EL8] What is the trend reactivity of s-block elements down and across the periodic table?
Down a group = more reactive Across a period = less reactive

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

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