A Level chemistry > definitions shuffled > Flashcards

definitions shuffled Flashcards

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1
Q

[AS 2.1] Define relative isotopic mass.

A

the mass of one atom of a particular isotope compared with one twelfth of the mass of a carbon-12 atom.

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2
Q

[AS 7.1] Define dynamic equilibrium.

A

The forward and reverse reactions happen at equal rates, so the concentrations of reactants and products stay constant in a closed system

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3
Q

[AS 7.2] Define a weak acid.

A

A weak acid is one that is only partially dissociated in aqueous solution.

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4
Q

[AS 7.2] Define a weak base.

A

A proton acceptor that partially dissociated in aqueous solution.

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5
Q

[AS 7.1] Define a reversible reaction.

A

A reversible reaction is a reaction that can go in both forward and backward directions.

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6
Q

[AS 3.4] Define bond length.

A

Bond length is the internuclear distance between two covalently bonded atoms.

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7
Q

Relationship between Faraday constant, avogadros constant and charge of electron

A

F = eL

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8
Q

[AS 5.1] Define standard enthalpy change of formation (ΔHf°).

A

It is the enthalpy change when one mole of a compound is formed from its constituent elements in their standard states under standard conditions. Can be Exothermic and Endothermic

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9
Q

[AS 13.2] Define saturated.

A

Saturated means containing only carbon–carbon single bonds.

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10
Q

Define Rf Value

A

the ratio of the distance a substance travels to the distance the solvent travels

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11
Q

[AS 2.3] Define empirical formula.

A

An empirical formula shows the simplest whole-number ratio of atoms of each element in a compound.

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12
Q

[A2 23.3] Define entropy (S).

A

Entropy is the measure of the number of possible arrangements of particles and their energy in a system.

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13
Q

[AS 7.2] Define a Brønsted-Lowry acid.

A

A Brønsted-Lowry acid is a proton donor.

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14
Q

[A2 37.2] Define retention time.

A

Retention time is the time taken for a substance to travel through the column and be detected on chromatograph

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15
Q

[A2 24.2] Define standard cell potential, E°cell.

A

The EMF of the cell made from two electrodes under standard conditions. Standard conditions being 298K, 1moldm^-3

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16
Q

[AS 7.2] Define an alkali.

A

An alkali is a base that dissolves in water to produce hydroxide ions, OH−.

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17
Q

[AS 5.1] Define standard enthalpy change of combustion (ΔHc°).
- Exo or Endo

A

It is the enthalpy change when one mole of a substance is completely burned in oxygen under standard conditions. Only Exothermic

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18
Q

[A2 25.1] Define a conjugate base.

A

A conjugate base is the species formed when an acid loses a proton.

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19
Q

[AS 13.4] Define geometrical isomerism.

A

Geometrical isomerism is stereoisomerism caused by restricted rotation due to presence of pi bonds in C=C double bond. Two different groups must be bonded to each of the carbon atoms

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20
Q

[AS 7.1] State Le Chatelier’s principle.

A

If a change is made to a system at dynamic equilibrium, the position of equilibrium moves to minimise that change.

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21
Q

[AS 5.1] Define standard conditions.

A

Standard conditions are 298 K and 101 kPa

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22
Q

[AS 13.2] Define unsaturated.

A

Unsaturated means containing at least one carbon–carbon double bond or triple bond.

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23
Q

Define intermediate

A

a species formed during a multi-step reaction mechanism that is used in the next step to form the final product

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24
Q

[AS 2.1] Define the unified atomic mass unit (u).

A

It is one twelfth of the mass of a carbon-12 atom.

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25
[A2 25.1] Define a conjugate acid.
A conjugate acid is the species formed when a base gains a proton.
26
[AS 13.4] Define structural isomerism.
Structural isomerism is when compounds have the same molecular formula but different structural formulas.
27
Describe a Standard Hydrogen Electrode
A half-cell used as a reference electrode and consists of : - Hydrogen gas in equilibrium with H+ ions of concentration 1.00 mol dm-3 and - Inert platinum electrode that is in contact with hydrogen gas and H+ ions
28
[A2 23.1] Define first electron affinity (EA). - Exo or Endo?
enthalpy change when 1 mole of electrons is added to 1 mole of gaseous atoms, to form 1 mole of gaseous 1- ions under standard conditions. Only Exothermic
29
List the three structural isomers
- Chain - Positional - Functional Group
30
[AS 13.2] Define a nucleophile.
A nucleophile is an electron-pair donor.
31
[AS 6.1] Define disproportionation.
Disproportionation is a redox reaction in which the same species is both oxidised and reduced.
32
[A2 27.1] Define a transition element.
A transition element is a d-block element that forms one or more stable ions with incomplete d orbitals.
33
[AS 2.1] Define relative atomic mass (Ar).
the weighted average mass of an atom of an element compared with one twelfth of the mass of a carbon-12 atom.
34
[A2 29.4] Define a racemic mixture.
A racemic mixture is a 1:1 mixture of two enantiomers.
35
[AS 3.2] Define ionic bonding.
Ionic bonding is the electrostatic attraction between oppositely charged ions.
36
[AS 8.3] Define a heterogeneous catalyst.
A heterogeneous catalyst is in a different physical state from the reactants.
37
[AS 13.2] Define homolytic fission.
Homolytic fission is bond breaking in which one electron from the bond goes to each atom, forming radicals.
38
[A2 29.4] Define optically active.
Optically active means able to rotate plane-polarised light.
39
[A2 37.2] Define the mobile phase in gas-liquid chromatography.
The mobile phase is an unreactive gas that carries the sample through the column.
40
[A2 23.2] Define enthalpy change of hydration (ΔHhyd). - Exo or Endo
It is the enthalpy change when one mole of gaseous IONS dissolves in water to form one mole of aqueous ions. Only Exothermic
41
[AS 13.4] Define stereoisomerism.
Stereoisomerism is when compounds have the same structural formula but a different arrangement of atoms in space.
42
[A2 28.5] Define the stability constant, Kstab.
The equilibrium constant for the formation of the complex ion in a solvent
43
[AS 2.1] Define relative molecular mass (Mr).
average mass of one molecule compared with one twelfth of the mass of a carbon-12 atom.
44
[A2 25.1] Define Ka.
Ka = [H+][A-] / [HA]
45
[AS 13.2] Define a free radical.
A free radical is a species with an unpaired electron.
46
[A2 23.1] Define lattice energy (ΔHlatt).
The enthalpy change when 1 mole of an ionic compound is formed from its gaseous ions (under standard conditions)
47
[AS 3.4] Define covalent bonding.
electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.
48
[AS 2.2] Define the Avogadro constant.
The Avogadro constant is the number of particles in one mole of a substance: 6.02 × 10^23 mol^-1.
49
[AS 1.1] Define first ionisation energy.
he energy required to remove one mole of electrons from one mole of gaseous atoms of an element to form one mole of gaseous 1+ ions
50
[A2 28.3] Define degenerate orbitals.
Degenerate orbitals are orbitals that have the same energy.
51
[AS 2.3] Define molecular formula.
A molecular formula shows the actual number of atoms of each element in one molecule.
52
[AS 5.1] Define standard enthalpy change of neutralisation (ΔHneut°). - Exo or Endo
It is the enthalpy change when one mole of water is formed by the reaction of an acid with an alkali under standard conditions. Only Exothermic
53
[A2 37.2] Define the stationary phase in gas-liquid chromatography.
The stationary phase is a high-boiling non-polar liquid spread on a solid support.
54
[AS 7.2] Define neutralisation.
Neutralisation is the reaction in which H+ ions react with OH− ions to form water.
55
[AS 5.1] Define standard enthalpy change of reaction (ΔHr°). - Exo or Endo
The enthalpy change when the reactants in the stoichiometric equation react to form the products under standard states. Can be Exothermic and Endothermic
56
[A2 28.2] Define coordination number.
Coordination number is the number of coordinate bonds formed to the central metal ion.
57
[A2 28.3] Define non-degenerate orbitals.
Non-degenerate orbitals are orbitals that have different energies.
58
[AS 13.4] Define a chiral centre.
A chiral centre is a carbon atom bonded to four different atoms or groups.
59
[AS 3.1] Define electronegativity.
Electronegativity is the power of an atom to attract electrons to itself
60
[A2 26.1] Define half-life, t1/2.
Half-life is the time taken for the concentration of a reactant to fall to half its value.
61
[A2 29.3] What is aromatic stabilisation?
Aromatic stabilisation is the extra stability of an aromatic ring caused by delocalisation of its pi electrons.
62
[A2 26.1] Define overall order of reaction.
Overall order is the sum of the powers of the reactant concentrations in the rate equation.
63
[A2 37.1] Define the solvent front.
The solvent front is the furthest point reached by the solvent on the chromatogram.
64
[A2 23.4] Define Gibbs free energy change (ΔG).
Gibbs free energy change is the energy change that determines feasibility and is given by ΔG = ΔH − TΔS.
65
[A2 24.1] Define electrolysis.
Electrolysis is the decomposition of an ionic substance by the passage of electric current.
66
[AS 2.1] Define relative formula mass.
Relative formula mass is the mass of one formula unit compared with one twelfth of the mass of a carbon-12 atom.
67
[AS 7.2] Define a Brønsted-Lowry base.
A Brønsted-Lowry base is a proton acceptor.
68
[A2 37.1] Define the stationary phase in thin-layer chromatography, give example
The stationary phase is the solid phase fixed in place on the plate, for example Al2O3 on a solid support.
69
[AS 7.2] Define a strong base.
A strong base is one that is fully dissociated in aqueous solution.
70
[A2 26.1] Define the rate constant, k.
The rate constant is the proportionality constant in the rate equation for a reaction at a given temperature.
71
[AS 13.2] Define an electrophile.
An electrophile is an electron-pair acceptor.
72
[AS 3.3] Define metallic bonding.
Metallic bonding is the electrostatic attraction between positive metal ions and delocalised electrons.
73
[AS 2.2] Define the mole.
A mole is the amount of substance that contains the Avogadro constant number of particles.
74
[A2 37.1] Define the mobile phase in thin-layer chromatography.
The mobile phase is the solvent that moves through the stationary phase.
75
[A2 28.2] Define a ligand.
A ligand is a species with a lone pair of electrons that forms a dative covalent bond to a central metal atom or ion.
76
[A2 28.2] Define a complex.
A complex is a molecule or ion formed by a central metal atom or ion surrounded by one or more ligands.
77
[A2 26.1] Define a rate-determining step.
A rate-determining step is the slowest step in a multi-step reaction mechanism.
78
[A2 23.2] Define enthalpy change of solution (ΔHsol). - Exo or Endo
It is the enthalpy change when one mole of a substance dissolves in enough water to form an infinitely dilute solution. Can be Exothermic and Endothermic
79
[AS 3.4] Define a coordinate (dative covalent) bond.
A coordinate bond is a covalent bond in which both electrons in the shared pair come from the same atom.
80
[A2 37.4] Define a deuterated solvent.
A solvent in which ordinary hydrogen is replaced by deuterium so the solvent does not interfere the proton NMR spectrum.
81
[A2 25.1] Define a conjugate acid-base pair.
A conjugate acid-base pair is two species that differ by one proton.
82
[A2 25.1] Define Kw.
Kw is the ionic product of water: Kw = [H+][OH−].
83
[AS 6.1] Define an oxidising agent.
An oxidising agent causes another species to be oxidised and is itself reduced.
84
[AS 13.2] Define hydrolysis.
Hydrolysis is bond breaking by reaction with water or hydroxide ions.
85
[A2 23.4] What does it mean if ΔG is negative?
A negative ΔG means the reaction or process is feasible under the stated conditions.
86
[A2 23.1] Define enthalpy change of atomisation (ΔHat). - Endo or Exo
It is the enthalpy change when one mole of gaseous atoms is formed from the element in its standard state. Only Enthothermic
87
[AS 7.2] Define a strong acid.
A strong acid is one that is fully dissociated in aqueous solution.
88
[A2 24.2] Define standard electrode (reduction) potential, E°.
The e.m.f. of a half-cell measured relative to the standard hydrogen electrode under standard conditions
89
[AS 3.4] Define bond energy.
Bond energy is the energy required to break one mole of a specified covalent bond in the gaseous state.
90
[AS 6.1] Define a reducing agent.
A reducing agent causes another species to be reduced and is itself oxidised.
91
[AS 13.2] Define a homologous series.
A homologous series is a family of organic compounds with the same functional group and the same general formula
92
[A2 25.1] Define a buffer solution.
A buffer solution is a solution that resists changes in pH when small amounts of acid or alkali are added.
93
[AS 3.6] Define bond polarity.
Bond polarity is the unequal sharing of bonding electrons caused by a difference in electronegativity between the bonded atoms.
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