Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

chemistry > Definitions > Flashcards

Definitions Flashcards

You may prefer our related Brainscape-certified flashcards:
AP® Chemistry flashcards Periodic Table flashcards
1
Q

CIS/TRANS ISOMERISM

A

A special case of E/Z isomerism in which two of the substituent groups attached to each carbon atom of the C=C group are the same (these are often, but not always, a H atom).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

REDUCING AGENT

A

A reagent which reduces another species (and is itself oxidised) by losing electrons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

PRECIPITATE

A

An insoluble solid formed when two solutions are mixed together.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

DYNAMIC EQUILIBRIUM

A

Exists in a closed system when the rate of ten forward reaction is equal to the rate of the reverse reaction and the concentrations of reactants and products do not change.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

AVERAGE BOND ENTHALPY

A

The average enthalpy change for the breaking of one mole of bonds in gaseous molecules (by homolytic fission).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

BASE (BRONSTED-LOWRY)

A

Proton acceptor.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

ATOMIC NUMBER

A

The number of protons in the nucleus of an atom.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Le CHATELIER’S PRINCIPAL

A

When a system in dynamic equilibrium is subjected to a change, the position of equilibrium will shift to minimise the effects of the change.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

STRONG ACID

A

A proton donor which completely dissociates into its ions in solution.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

OXIDISING AGENT

A

A reagent which oxidises another species (and is itself reduced) by gaining electrons.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

ENTHALPY CHANGE

A

The amount of heat released (or absorbed) by a chemical reaction, carried out at constant pressure. Units: kJ mol-1.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

PI () BOND

A

Double sideways overlap of adjacent p orbitals above and below the plane of the bonding atoms, with restricted rotation of the bond.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

METALLIC BONDING

A

The strong electrostatic attraction between metal cations (positive ions) and delocalised electrons (in a giant metallic lattice structure).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

CATALYST

A

Increases the rate of a reaction without being used up by the overall reaction. It allows the reaction to proceed via a different route with lower activation energy.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

OXIDATION

A

The loss of electrons / an increase in oxidation number (state).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

RETENTION FACTOR

A

Distance moved by the component (from base line)/distance moved by solvent front (from base line).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

OXIDATION REACTION

A

A reaction where oxygen is added and/ or hydrogen is removed from a molecule.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

STRUCTURAL ISOMERS

A

Compounds with the same molecular formula but different structural formulae.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

ALICYCLIC

A

An aliphatic compound arranged in non-aromatic rings with or without side chains.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

STANDARD ENTHALPY CHANGE OF HYDRATION

A

The enthalpy change that takes place when one mole of isolated gaseous ions is dissolved in water forming one mole of aqueous ions under standard conditions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

(GIBBS) FREE ENERGY CHANGE

A

The balance between the enthalpy change (ΔH), the entropy change (ΔS) and temperature (T) for a process. ΔG = ΔH - TΔS ΔG, determines the feasibility of a reaction: a reaction is feasible if ΔG < 0.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

SALT

A

A compound produced when a H+ ion from an acid is replaced by a metal ion or another positive ion, such as the ammonium ion.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

CHROMATOGRAPHY

A

An analytical technique that separates components in a mixture between a mobile phase and a stationary phase.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

ANHYDROUS

A

Describes a substance that does not contain water.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

DEGRADABLE POLYMER

A

A polymer that breaks down into smaller fragments when exposed to light, heat or moisture.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

IONIC PRODUCT OF WATER

A

The dissociation of water: H2O H+ + OH- Kw = [H+] [OH-] units = mol2dm-6 At 250C Kw = 1.00 x 10-14 mol2dm-6.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

HYDRATED

A

When water of crystallisation is present in a crystal compound.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

MOBILE PHASE

A

The phase which moves in chromatography; a liquid (TLC) or a gas (GC).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

MOLECULAR FORMULA

A

The actual number and type of atoms of each element in a molecule.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

DISPLACEMENT REACTION

A

A reaction in which a more reactive element (halogen) displaces a less reactive element (halogen) from an aqueous solution of its halide ions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

PERIODICITY

A

The repeating pattern of chemical and physical properties across different periods.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

SIGMA () BOND

A

Single end-on (axial) overlap of orbitals directly between bonding atoms, allowing free rotation of the bond.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

COVALENT BOND

A

The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

RETENTION TIME

A

The time taken from a component to pass from the column inlet to the detector (in GC).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

STANDARD CELL POTENTIAL

A

Eθcell = Eθreduction - Eθoxidation For a reaction to be feasible, the species undergoing reduction must have the more positive Eθ value: Eθcell > 0.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

ACID (BRONSTED-LOWRY)

A

Proton donor.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

MOLE FRACTION

A

Number of moles of A/total number of moles in gas mixture.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

ALIPHATIC

A

A compound containing carbon and hydrogen joined together in straight chains, branched chains or non-aromatic rings.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

STANDARD ENTHALPY CHANGE OF SOLUTION

A

The enthalpy change when one mole of a compound is completely dissolved in water under standard conditions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

ENDOTHERMIC REACTION

A

A reaction where heat energy is absorbed from the surroundings. (ΔH is positive).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

CURLY ARROW

A

The movement of an electron pair, showing either heterolytic fission or formation of a covalent bond.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

MOLE

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

STEREOISOMER

A

Compounds with the same structural formula but with a different arrangement of the atoms in space.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

DEHYDRATION REACTION

A

A reaction where a H2O molecule is removed from a saturated molecule to form an unsaturated molecule.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

RATE OF REACTION

A

The change in concentration of a reactant or product per unit time.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

EXOTHERMIC REACTION

A

A reaction where heat energy is released to the surroundings. (ΔH is negative).

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

OPTICAL ISOMERISM

A

An example of stereoisomerism in which there is a pair of non-superimposable mirror images of one another, about a chiral centre.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

HOMOLYTIC FISSION

A

The breaking of a covalent bond where each bonding atom receives one electron from the bonding pair of electrons, forming two radicals.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

RELATIVE ISOTOPIC MASS

A

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

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

IONIC BOND

A

The electrostatic attraction between positive and negative (oppositely charged) ions.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

STRUCTURAL FORMULA

A

The minimum detail required to show the arrangement of atoms in a molecule, e.g. for butane: CH3CH2CH2CH3 or CH3(CH2)2CH3.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

DISPLAYED FORMULA

A

shows the relative positioning of atoms and the bonds between them, e.g. for ethanol:

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

AROMATIC

A

A compound containing a benzene ring.

54
Q

LIGAND

A

A molecule or ion that can donate a pair of electrons with the transition metal ion to form a coordinate bond.

55
Q

COORDINATION NUMBER

A

The total number of coordinate bonds formed between a central metal ion and its ligands.

56
Q

MOLAR GAS VOLUME

A

The gas volume per mole of a substance. This is 24.0 dm3mol-1 at room temperature and pressure (RTP).

57
Q

-AMINO ACID

A

Molecule with general formula RCH(NH2)COOH.

58
Q

HYDROCARBON

A

Compounds composed of only carbon and hydrogen.

59
Q

DATIVE (CO-ORDINATE BOND)

A

The strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms, where only one of the atoms supplies both the electrons shared.

60
Q

CONDENSATION POLYMERISATION

A

The joining of monomers with the elimination of a small molecule such as water.

61
Q

ALKALI

A

A base that dissolves in water and releases OH- ions in aqueous solution.

62
Q

WATER OF CRYSTALLISATION

A

Water molecules that are bonded into a crystalline structure of a compound.

63
Q

REDUCTION

A

The gain of electrons / a decrease in oxidation number (state).

64
Q

AVOGADRO’S CONSTANT

A

The number of particles per mole of a substance (6.02 x 1023 mol-1).

65
Q

STANDARD STATES

A

Physical states under standard conditions.

66
Q

STATIONARY PHASE

A

The phase that does not move in chromatography; a solid (TLC) or a liquid on a solid support (GC).

67
Q

MASS NUMBER

A

The total number of protons and neutrons in the nucleus of an atom.

68
Q

UNSATURATED

A

Containing at least one multiple carbon-carbon bond, including C=C, C=C and aromatic rings.

69
Q

d-BLOCK ELEMENT

A

Element which has the highest energy electron in a d sub-shell (or d orbital).

70
Q

LIGAND SUBSTITUTION

A

A reaction in which one ligand in a complex ion is replaced by another ligand.

71
Q

TRANSITION ELEMENT

A

d block element that has an ion with an incomplete d sub-shell.

72
Q

HETEROLYTIC FISSION

A

The breaking of a covalent bond where one bonding atom receives both electrons from the bonding pair of electrons, forming two oppositely charged ions.

73
Q

DISTILLATION

A

The technique of heating a liquid to create vapour which is collected when cooled and condensed, separate from the original liquid. (often used to separate liquids based on their boiling points).

74
Q

SKELETAL FORMULA

A

The simplified organic formula, shown by ‘hiding’ every C atom and any H atom which is directly attached to a C atom, leaving just the carbon skeleton and any functional groups. e.g. for butan-2-ol:

75
Q

VOLATILITY

A

The ease with which a liquid turns into a gas.

76
Q

CONJUGATE ACID-BASE PAIR

A

A pair of two species that transform into each other by the gain or loss of a proton (H+).

77
Q

RELATIVE ATOMIC MASS

A

The weighted mean mass of an atom of an element compared with one-twelfth of the mass of an atom of carbon-12.

78
Q

RATE EQUATION

A

Gives the relationship between the rate of reaction and the concentration of the reactants raised to the powers of their orders. Example, for the reaction: A + B products Rate equation: rate = k [A]m [B]n.

79
Q

FIRST IONISATION ENERGY

A

The energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions.

80
Q

SATURATED

A

Containing single carbon-carbon bonds only.

81
Q

ATOMIC ORBITAL

A

A region around the nucleus that can hold up to two electrons, with opposite spins.

82
Q

HESS’ LAW

A

The enthalpy change of a reaction depends only on the initial and final states and is independent of the route taken.

83
Q

ELECTRON PAIR REPULSION THEORY

A

• The shape of simple covalent molecules and ions are determined by the number & type of electron pairs around the central atom.
• Electron pairs repel one another as far apart as possible • Lone pairs of electrons repel more strongly than bond pairs of electrons.

84
Q

FUNCTIONAL GROUP

A

A group of atoms within a molecule responsible for the characteristic reactions of a compound.

85
Q

DISPROPORTIONATION

A

A reaction in which the same element is both oxidised and reduced.

86
Q

CONDENSATION REACTION

A

A reaction where an H2O molecule is lost when two molecules join together.

87
Q

BUFFER SOLUTION

A

A system that minimises pH changes on addition of small amounts of an acid or a base.

88
Q

OXIDATION NUMBER

A

A measure of the number of electrons that an atom uses to bond with atoms of another element.

89
Q

LATTICE ENTHALPY

A

The enthalpy change when one mole of an ionic compound is formed from its gaseous ions under standard conditions

90
Q

ADDITION REACTION

A

A reaction where a group is added across a double bond of an unsaturated molecule to make a saturated molecule (one product).

91
Q

RATE-DETERMINING STEP

A

The slowest step of a reaction mechanism of a multi-step reaction.

92
Q

HOMOLOGOUS SERIES

A

A series of organic compounds with the same functional group but with each successive member differing by CH2.

93
Q

STANDARD CONDITIONS

A

• Temperature = 25 oC (298 K)
• Pressure of gases = 1 atm (100 kPa)
• Concentration of (aq) solutions = 1.00 moldm-3

94
Q

STANDARD ENTHALPY CHANGE OF FORMATION

A

The enthalpy change that takes place when one mole of a compound is formed from its constituent elements in their standard states under standard conditions.

95
Q

STANDARD ENTHALPY OF COMBUSTION

A

The enthalpy change when 1 mole of a substance is completely burned in oxygen under standard conditions.

96
Q

SOLUTION

A

A homogeneous mixture composed of two or more substances. A solution consists of a solute and a solvent. The solute is the substance that is dissolved in the solvent. These are usually transparent.

97
Q

CHIRAL CENTRE (carbon)

A

A carbon atom with four different groups attached.

98
Q

SUCCESSIVE IONISATION ENERGY

A

A measure of the energy required to remove each electron in turn.

99
Q

COMPLEX ION

A

A transition metal ion bonded to one or more ligands by coordinate bonds (dative covalent bonds).

100
Q

STANDARD ELECTRODE (REDOX) POTENTIAL

A

The e.m.f. (electromotive force / voltage) of a half cell compared with a standard.

101
Q

ELECTRONEGATIVITY

A

The ability of an atom to attract the bonding electrons towards itself in a covalent bond.

102
Q

HEAT UNDER REFLUX

A

The continuous boiling and condensing of a liquid (in a condenser) preventing loss of volatile liquids from a heated reaction vessel.

103
Q

HYDROLYSIS REACTION

A

A chemical reaction involving water or an aqueous solution, which causes the breaking of a bond, splitting a reactant molecule into two products.

104
Q

ACTIVATION ENERGY

A

The minimum energy required for a reaction to take place, by the breaking of bonds in the reactants.

105
Q

HETEROGENEOUS CATALYST

A

Catalyst has a different physical state from the reactants (frequently, reactants are gases while the catalyst is a solid).

106
Q

ALKYL GROUP

A

Of formula CnH2n+1.

107
Q

HALF-LIFE

A

The time taken for the concentration of a reactant to fall to half of its original concentration. (For a first order reaction, half-life is constant).

108
Q

BIDENTATE LIGAND

A

A ligand which can donate two lone pairs of electrons to the central metal ion to form two coordinate bonds.

109
Q

HOMOGENEOUS CATALYST

A

Catalyst is in the same physical state as the reactants (frequently, the aqueous or gaseous state).

110
Q

RATE CONSTANT

A

: ‘k’ in the rate equation: the larger the value of k, the faster the reaction. k is constant at a constant temperature and increases with temperature (Arrhenius).

111
Q

ISOTOPES

A

Atoms of the same element with different numbers of neutrons.

112
Q

PARTIAL PRESSURE

A

mole fraction of A x total pressure P.

113
Q

GENERAL FORMULA

A

The simplest algebraic formula for any member of a homologous series, e.g. for an alkane: CnH2n+2.

114
Q

FUEL CELL

A

A cell which uses the energy from the reaction of a fuel with oxygen to create a voltage.

115
Q

ELIMINATION REACTION

A

A reaction where an atom or group is removed from a molecule to make an unsaturated molecule.

116
Q

EMPIRICAL FORMULA

A

The simplest whole number ratio of atoms of each element present in a compound.

117
Q

REDOX

A

A reaction where both oxidation and reduction take place.

118
Q

E/Z ISOMERISM

A

An example of stereoisomerism in which there is restricted rotation about a C=C double bond, and each carbon atom of the C=C double bond has two different groups attached to it.

119
Q

STANDARD ENTHALPY OF NEUTRALISATION

A

The energy change that accompanies the neutralisation of an aqueous acid by an aqueous base to form one mole of H2O(l), under standard conditions.

120
Q

NUCLEOPHILE

A

An electron pair donor.

121
Q

MOLAR MASS

A

The mass in grams of one mole of a substance.

122
Q

STANDARD ENTHALPY CHANGE OF REACTION

A

The enthalpy change that accompanies a reaction in the molar quantities expressed in a chemical equation under standard conditions, all reactants and products being in their standard states.

123
Q

RADICAL

A

Species with an unpaired electron (e.g. Cl.)

124
Q

ENTROPY

A

A measure of the dispersal of energy in a system which is greater, the more disordered a system.

125
Q

ORDER

A

How the concentration of a reactant affects the rate of the reaction. In the rate equation above, Order with respect to A = m Order with respect to B = n Overall order = m + n.

126
Q

EQUILIBRIUM CONSTANT

A

For an equilibrium reaction: A + B C + D Kc = [C]c [D]d Kp = p(C)c x p(D)d [A]a [B]b p(A)a x p(B)b [ ] = equilibrium concentrations p = partial pressures (for gases).

127
Q

ACID DISSOCIATION CONSTANT

A

For a weak acid: HA H+ + A- Ka = [H+] [A-] units = moldm-3 [HA] and pKa = - log Ka.

128
Q

BIODEGRADABLE POLYMER

A

A polymer that breaks down completely into CO2 and H2O.

129
Q

ELECTROPHOLE

A

An electron pair acceptor.

130
Q

p-BLOCK ELEMENT

A

Element which has the highest energy electron in a p sub-shell (or p orbital) (Applies to any element; s-, p-, d- or f-block).

131
Q

WEAK ACID

A

A proton donor which partially dissociates into its ions in solution. pH pH = - log [H+] and [H+] = 10-pH.

132
Q

SUBSTITUTION REACTION

A

A reaction where an atom or group in a molecule is replaced by another atom or group.

chemistry (40 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions