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AQA - Chemistry Unit 4 > Definitions > Flashcards

Definitions Flashcards

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1
Q

Achiral molecule

A

A molecule that can be superimposed on its mirror image

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2
Q

Acid anhydride

A

A molecule formed from two identical carboxylic acid molecules joined via an oxygen atom

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3
Q

Acid dissociation constant (Ka)

A

An equilibrium constant specific to weak acids that relates the acid concentration to the concentration of [H⁺] ions.
Ka = [H⁺]{HA⁻] ÷ [HA]

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4
Q

Acidic buffer

A

A buffer with pH of less than 7 made by mixing a weak acid with one of its salts.

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5
Q

Acyl chloride

A

A molecule which contains the functional group COCl

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6
Q

Addition polymer

A

A type of polymer formed by joining small alkenes together

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7
Q

Amide

A

A carboxylic acid derivative which contains the functional group CONH₂

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8
Q

Amine

A

A molecule where one or more of the hydrogen atoms in ammonia have been replaced with an organic functional group

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9
Q

Amino acid

A

A molecule with an amino group (NH₂) and a carboxyl group (COOH)

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10
Q

Basic buffer

A

A buffer with pH of more than 7 made by mixing a weak base with one of its salts

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11
Q

Biodiesel

A

A mixture of methyl esters of fatty acids which can be used as a carbon neutral fuel

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12
Q

Cationic surfactant

A

A surfactant which is positively charged

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13
Q

Chemical shift

A

Nuclei in different environments absorb energy of different frequencies. NMR spectroscopy measures these differences relative to a standard substance - this difference is called the chemical shift.

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14
Q

Chromatography

A

An analytical technique which uses a mobile phase and a stationary phase to separate out mixtures

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15
Q

Deuterated solvent

A

A solvent which has had all of its hydrogen atoms exchanged for deuterium atoms.

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16
Q

Deuterium

A

An isotope of hydrogen. It contains one neutron, one proton and one electron.

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17
Q

Electrophile

A

An electron deficient (usually positively charged) species which is attracted to regions of high electron density

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18
Q

Electrophilic substitution

A

A reaction mechanism when an electrophile substitutes for a hydrogen atom in a molecule

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19
Q

Enantiomer

A

A molecule that has the same structural formula as another molecule but with four groups arranged around a chiral carbon compound atom so that it is a non-superimposable mirror image of the other molecule.

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20
Q

Ester

A

A molecule that contains the functional group RCOOR

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21
Q

Esterification

A

Forming an ester by heating a carboxylic acid and an alcohol in the presence of a strong acid catalyst

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22
Q

Equilibrium constant Kc

A

A ratio worked out from the concentration of the products and reactants once a reversible reaction has reached equilibrium

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23
Q

Fatty acid

A

A long chain carboxylic acid which can combine with glycerol to for a fat or an oil

24
Q

Fragment ion

A

A charged fragment produced when a molecular ion breaks up inside a mass spectrometer

25
Q

Infrared (IR) spectroscopy

A

An analytical technique used to identify the functional groups present in a molecule by measuring the frequency of energy absorbed by its bonds

26
Q

Integration trace

A

A line on an ¹H NMR spectrum that has a change in height that is proportional to the area of the peak it’s next to

27
Q

Ionic product of water Kw

A

A constant generated by multiplying the Hc for the dissociation of water by [H₂O]
Kw = [H⁺][OH⁻]

28
Q

Isoelectric point

A

The pH at which the average overall charge on a molecule is zero

29
Q

M peak

A

The peak on a mass spectrum that is caused my the molecular ion

30
Q

Mass spectrometry

A

An analytical technique used to find the structure of a molecule by looking at the pattern of ions it produces when it is bombarded with electrons

31
Q

Mass spectrum

A

A chart produced by a mass spectrometer giving information on relative isotopic mass and relative abundance of isotopes.

32
Q

Mobile phase

A

A liquid or gas in chromatography which contains molecules that can move

33
Q

n+1 rule

A

Peaks on a ¹H NMR spectrum always split into the number of hydrogens on the neighbouring carbon, plus one

34
Q

N-substituted amides

A

A amide where one of the hydrogens attached to the nitrogen has been substituted with another functional group

35
Q

Nitration

A

A reaction in which a nitro group (NO₂) is added to a molecule

36
Q

Nuclear Magnetic Resonance (NMR) spectroscopy

A

An analytical technique which uses the nuclear spin of a nucleus to determine the relative environment of the nucleus in a compound.

37
Q

Nuclear spin

A

Any nucleus that contains an odd number of protons and neutrons will spin on its axis creating a weak magnetic field.

38
Q

Nucleophile

A

A species that forms a bond with an electrophile by donating a pair of electrons

39
Q

Nucleophilic addition

A

A reaction mechanism where a nucleophile adds on to the partially positive carbon atom of a carbonyl compound

40
Q

Nucleophilic addition-elimination

A

A reaction mechanism where a nucleophile adds onto the partially positive carbon atom of a carbonyl compound and another nucleophile is eliminated.

41
Q

Nucleophilic substitution

A

A reaction mechanism where a nucleophile substitutes for an atom (or group of atoms) in a molecules

42
Q

Optical isomer

A

A molecule that has the same structural formula as another molecule but with four groups arranged around a chiral carbon atom that is a non-superimposable mirror image of the other molecule

43
Q

Paper chromatography

A

A technique which can used to separate out mixtures of different compounds

44
Q

pH

A

A measure of the hydrogen ion concentration in solution

pH = -log[H⁺]

45
Q

Plane-polarised light

A

Light in which all the waves are vibrating in the same plane

46
Q

Polyamide

A

A polymer formed from reactions between dicarboxylic acids and diamines

47
Q

Polyester

A

A polymer formed from reactions between dicarboxylic acids and diols

48
Q

Polypeptide

A

A polymer formed from reactions between amino acids

49
Q

Racemate

A

A mixture that contains equal quantities of each enantiomer of an optically active compound

50
Q

Rate constant (k)

A

A constant in the rate equation. The larger it is, the after the rate of reaction.

51
Q

Rate determining step

A

The slowest step in a reaction mechanism which determines to overall rate of reaction

52
Q

Retention

A

The process of being adsorbed onto the stationary phase in chromatography

53
Q

Retention time

A

The time taken for a component of a mixture to pass through a chromatography column to the detector at the other end

54
Q

Splitting pattern

A

Peaks in ¹H NMR spectra may be split into further peaks. The resultant group of peaks is called a splitting pattern

55
Q

Stationary phase

A

A solid, or a liquid held in a solid, used in chromatography which contains molecules that can’t move

56
Q

Surfactant

A

A compound which is partly soluble and partly insoluble in water

57
Q

Zwitterion

A

A dipolar ion which has both a negative and a positive charge in different parts of the molecule.

AQA - Chemistry Unit 4 (1 decks)

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