AS Vocabulary Flashcards
(166 cards)
1
Q
alkali
A
a base that is soluble in water
2
Q
acid
A
a proton (hydrogen ion) donor
3
Q
active site
A
the “pocket” on an enzyme surface where the substrate binds and undergoes catalytic reaction
4
Q
allotrope
A
different crystalline or molecular forms of the same element. Graphite and diamond are allotropes of carbon
5
Q
alloy
A
a misture of two or more metals or a metal with a non-metal
6
Q
amphoteric
A
able to behave as both an acid and a base. e.g.aluminium oxide
7
Q
atomic orbitals
A
regions of space outside the nucleus that can be occupied by one or, at most, two electron. orbitals are named s, p, d and f. they have different shapes
8
Q
average bond energy
A
a general bond energy value used for a particular bond, e.g. a C-H, when the exact bond energy is not required. average bond energies are often used because the strength of a bond between two particular types of atom is slightly different in defferent compounds
9
Q
Avogadro constant
A
the number of atoms ions molecules or electrons in a mole of atoms ions molecules or electrons. its numerical value is 6.02*10^23
10
Q
base
A
a proton (hydrogen ions) acceptor
11
Q
boiling point
A
the temperature at which the vapour pressure is equal to the atmospheric pressure
12
Q
Boltzmann distribution
A
a graph showing the distribution of energies of the particles in a sample given temperature
13
Q
bond energy/bond enthalpy
A
the energy needed to break 1 mole of a particular bond in 1 mole of gaseous molecules
14
Q
Bronsted-Lowry theory of acids
A
acids are proton donors and bases are proton acceptors
15
Q
catalyst
A
a substance that increases the rate of a reaction but remains chemically unchangeditself at he end of the reaction
16
Q
closed system
A
a system in which matter or energy is not lost or gained, e.g. gases in a closed vessel
17
Q
compound
A
a substance made up of two or more elements bonded together
18
Q
condensation
A
the change in state when a vapour changes to a liquid
19
Q
conjugate pair (acid/base)
A
an acid and base on each side of an equilibrium equation that are related to each other by the difference of exactly one proton; e.g. the acid in the forward reaction and the base in the reverse reaction or the base in the forward reaction and the acid in the backward reaction
20
Q
co-ordinate bond/dative covalent bond
A
a covalent bond in which both electrons in the ond come from the same atom
21
Q
covalent bond
A
a bond formed by the sharing of pairs of electrons between two atoms
22
Q
degenerate orbitals
A
atomic orbitals at the same energy level
23
Q
delocalised electrons
A
electrons that are not associated with a particular atom - they can move between tree or more adjacent atoms
24
Q
denaturation
A
the process by which the three-dimensional structureof a protein or other biological macromolecule is change, often irreverisbly. relatively high temperature, extremes of pH and organic solvents often cause denaturation
25
dipole
a separation of charge in a molecule. one end of the molecule is permanently positively charged and the other is negatively charged
26
displayed formula
a drawing of a molecule that shows all the atoms and bonds within the molecule
27
dissociation
the break-up of a molecule into ions, for example when HCl molecules dissolve in aqueous solution, they dissociate completely into H+ and Cl- ions
28
dot-and-cross diagram
a diagram showing the arrangement of the outer-shell electrons in an ionic or covalent element or compound. the electrons are shown as dots or crosses to show their origin
29
double covalent bond
two shared pairs of electrons bonding two atoms together
30
dynamic equilibrium
in an equilibrium mixture, molecules of reactants are being converted to products at the same rate as products are being converted to reactants
31
electron
tiny subatomic particles found in orbitals around the nucleus. they have a negative charge but have negligible mass
32
electronegativity
the ability of an atom to attract the bonding electrons in a covalent bond
33
electronic configuartion
a way of representing the arrangement of the electrons in atoms showing the principal quantum shells, the subshells and the number of electrons present, e.g. 1s22s22p3. the electrons may also be shown in boxes
34
electrovalent bond/ionic bond
the elctrostativ attraction between oppositely charged ions
35
element
a substance made of only one type of atom
36
empirical formula
the formula that tells us the simplest ratioo of the different atoms present in a molecule
37
endothermic
term used to describe a reaction in which energy is absorbed from the surroundings: the enthalpy change is positive
38
energy levels (of electrons)
the regions at various distances from the nucleus in which electrons have a particular amount of energy. electrons further from the nucleus have more energy.
39
enthalpy change of atomisation
the enthalpy change when 1 mole of gaseous atoms is formed from its element under standard conditions
40
enthalpy change of hydration
the enthalpy change when 1 mole of a specified gaseous ion dissolves in sufficient water to form a very dilute solution
41
enthalpy chane of solution
the enthalpy change when 1 mole of an ionic solid dissolves in sufficient water to form a very dilute solution
42
enthalpy change
the energy transferred in a chemical reaction. delta h
43
enthalpy cycle
a diagram showing alternative routes between reactants and products that allows the determination of one enthalpy change from other known enthalpy changs by using Hess's law
44
enthalpy profile diagram
a diagram showing the enthalpy change from reactants to products along the reaction pathway
45
enzyme
a protein molecule that is a biological catalyst. most act on a specific substrate
46
enzyme activity
measure of the rate at which substrate is converted to product in an enzyme-catalysed reaction
47
equilibrium constant
a constant calculated from the equilibrium expression for a reaction
48
equilibrium expression
a simple relationship that links Kc to the equilibrium concentrations of reactants and products and the storchiometric equation
49
equilibrium reaction
a reaction that does not go to completion and in which reactants and products are present in fixe concentration ratios
50
exothermic
a reaction in which energy is released to the surrounding: negative enthalpy change
51
fragmentation
the breading up of a molecule into smaller parts by the breading of covalent bonds in a mass spectrometer
52
general/ideal gas equation
an equation relating the volme of a gas to the temperature, pressure and number of moles of gas. ideal gas equation. pV=nRT
53
half-equation
in a redox reaction, an equation showing either an oxidation or a reduction
54
Hess's law
the total enthalpy change for a chemical reaction is independent of the route by which the reaction takes place
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heterogeneous catalysis
the type of catalysis in which the catalyst is in a different phase from the reactants. e.g. iron in Haber process
56
homogeneous catalysis
catalyst and reactants are in the same phase. e.g. sulfuric acid catalysing the formation of an ester from an alcohol and carboxylic acid
57
hybridisation of atomic orbitals
the proces of mixing atomic orbitals so that each has some character of each of the orbitals mixed
58
hydrogen bond
the strongest type of intermolecular force - it is formed between melecules having a hydrogen atom bonded to one of the most electronegative elements (F, O or N)
59
ideal gas
a gas whose volume varies in proportion to the temperature and in inverse proportion to the pressure.noble gases such as He and Ne approach ideal behaviour because of their low intermolecular forces.
60
intermolecular forces
the weak forces between molecules
61
ionisation energy, deltaHi
the energy needed to remove 1 mole of electrons from 1 of atoms of an element in the gaseous state to form 1 mole of gaseous ions
62
isotopes
atoms of an element with the same number of protons but different numbers of neutrons
63
kinetic theory
the theory that particles in gases and liquids are in constant movement. used to explain the effect of temperature and pressure on the volume of a gas as well as rates of chemical reactions
64
lattice
a regularly repeating arrangement of ions, atoms or molecules in 3D
65
le Chetelier's principle
when any of the conditions affecting the position of equilibrium are changed, the position of that equilibrium shifts to minimise the change
66
lone pairs (of electrons)
pairs of electrons in the outer shell of an atom that are not bonded
67
mass number/nucleon number
number of protons + number of neutrons
68
molar mass
the mass of a mole of substance in grams
69
mass spectrometer
an instrument for finding the relevant isotopic abundance of elements and to help identify unknow organic compounds
70
mole
the unit of amount of substance. the amount of substance that has the same number of particles (atoms, ions, molecules or electrons) as there are atoms in exactly 12g of the carbon-12 isotope
71
molecular formula
the formula that tells us the actual numbers of each type of atom in a molecule
72
neutron
a subatomic particle found in the nuvleus of an atom. it has no charge and has the same mass as a proton
73
non-polar
a molecule with no separation of charge; it will not be attracted to a positive or negative charge
74
nucleus
small dense core at the centre of every atom, containing protons (+1) and neutrons (0). always +
75
open system
a system in which matter is lost or gained. e.g. a mixture of solids and gases in an open beaker
76
oxidation
addition of oxygen, removal of electrons or increase in oxidation number of a substance; organic - reaction whcih oxygen atoms are added to a molecule/hydrogen atoms are removed
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oxidation number/state
a number given to an atom in a compound that describes how oxidised or reduced it is
78
oxidising agent
reactant that increase the oxidation # or removes e- from another reactant, reduced itself
79
partial pressure
pressure that an individual gas contributes to the overall pressure in a mixture of gases
80
permanent dipole-dipole force
type of intermolecular force between molecules that have permanent dipoles
81
pi bound
multiple covalent bond involving the sideways overlaping of p atomic orbitals
82
polar (covalent bond)
covalent bond in which the two bonding electrons are not shared equally by the atoms in the bond. the atom with the greater share of the electrons have a partial negative charge, delta-, and the other has a partial positive charge, delta+
83
principal quantum shells, n
regions at various distances from the nucleus that may contain up to a certain number of electrons. 1st quantum shell contains up to 2 e- and 2nd up to 8 and 3rd up to 18. 2n^2
84
proton
positively charged subatomic particle in the nucleus
85
rate of reaction
a measure of the rate at which reactants are used up or the rate at which products are formed. in moldm-3s-1
86
real gases
gases that do not obey the ideal gas law, espacially at low temperature and high pressure
87
redox reaction
a reation in which oxidation and reduction take place at the same time
88
reducing agent
reactant that decreases the oxidation number of or + e- to another reactant
89
relative formula mass
mass of one formula unit of a compound measured on a scale on which an atom of the carbon-12 isotope has a mass of exactly 12 units
90
relative isotopic mass
mass of a particular isotope of an element on a scale in which an atom of the carbon-12 isotope has a mass of exactly 12 units
91
relative molecular mass
mass of a molecule measured on a scale in which an atom of carbon-12 isotope has a mass of exactly 12 units
92
reversible reaction
reaction in which products can be changed back to reactants by reversing the conditions
93
shielding
the ability of innershells of electrons to reduce the effective nuclear charge on electrons in the outer shell
94
sigma bonds
single covalent bonds, formed by the 'end-on' overlap of atomic orbitals
95
specific
most enzymes are described as specific because they will only catalyse one reaction involving one particular molecule or pair of melecules
96
spectator ion
ion present in a reaction mixture that od not take part in the reaction
97
spin-pair repulsion
electrons repel each other as they have the same charge. electrons arrange themselves so that they first singly occupy different orbitals in the same sublevel.after that they pair up with their spins opposed to each other
98
standard condition
10^5 pascals (100 kPa), 298K (25 degree). used to compare moles of gases or enthalpy changes accurately
99
standard enthalpy change
an enthalpy change that takes place under standard conditions of pressure and temperature
100
state symbol
s, l, g, aq
101
stoichiometry
the mole ratio of the reactants and products in the balanced equation for a reaction
102
strong acid/base
an acid or base that is completely ionised in water
103
subshell
region within the principal quantum shells where electrons have more or less energy depending on their distance from the nucleus. s, p, d, f
104
substrate
a molecule that fits into the active site of an enzyme and reacts
105
successive ionisation energy, deltaHi1, deltaHi2
energy required to remove the first, second, third electrons and so no from a gaseous atom or ion, producing an ion with one more positive charge each time. in kJ per mole of ions produced
106
surrounding
in enthalpy changes, anything other than the chemical reactants and products, for example the solvent, the test tube in which the reaction takes place, the air around the test tube
107
titre
in a titration, the final burette reading minus the initial burette reading
108
triple covalent bond
3 shared pairs of e- bonding 2 atoms together
109
van der Waal's force
the weak forces of attraction between molecules caused by the formation of temporary dipoles
110
vaporisation
the change in stae when a liquid changes to vapour
111
vapour pressure
pressure exerted by a vapour in equilibrium with a liquid
112
weak acid/base
an acid or base that is only slightly ionised in water
113
acyl chloride
a reactive organic compound related to a carboxylic acid, with the OH group in the acid replaced by a Cl atom, for example ethanoyl chloride, CH3COCl
114
addition polymeristation
the reaction is which monomers containing carbon-to-carbon double bonds react together to form long-chain molecules called polymers
115
addition reaction
an organic reaction in which two reactant molecules combine to give a single product molecule
116
alkaline earth metals
the elements in Group 2 of the Periodic Table
117
alkanes
saturatedhydrocarbons with the general formula CnH2n+2
118
alkenes
unsaturated hydrocarbons with a carbon-carbon double bond. Their general formula is CnH2n
119
anion
a negatively charged ion
120
biofuels
renewable fuels, soured from plant or animal materials
121
carbocation
an alkyl group carrying a single positive charge on one of its carbon atoms, e.g. +CH2CH3
122
cation
a positively charged ion
123
chiral centre
a carbon atom with four different groups attached, creating the possibility of optical isomers
124
condensation reaction
a reaction in which two organic molecules join together and in the process eliminate a small molecule, such as water or hydrogen chloride
125
cracking
the process in which large, less useful hydrocarbon molecules are broken down into smaller, more useful molecules
126
dehydration
a reaction in which a water molecule is removed from a molecule, e.g. in the dehydration of an alcohol to give an alkene
127
disproportionation
the simultaneous reduction and oxidation of the same species in a chemical reaction
128
electrophile
a species that can act as an acceptor of a pair of electrons in an organic mechanism
129
elimination
a reaction in which a small molecule, such as H2O or HCl, is removed from an organic molecule
130
enhanced global warming
the increase in average temperatures around the world as a consequence of the huge increase in the amounts of CO2 and other greenhouse gases produced by human activity
131
esterification
the reaction between an alcohol and a carboxylic acid (or acyl chloride) to produce an ester and water
132
eutrophication
an environmental problem caused by fertilisers leached from fields into rivers and lakes. the fertiliser then promotes the growth of algae on the surface of water. when the algae die, bacteria thrive and use up the dissolved oxygen in the water, killing aquatic life
133
Fehling's solution
an alkaline solution containing copper(II) ions used to distinguish between aldehydes and ketones. a positive test is one in which the clear blue solution gives a red/orange precipitate when warmed with aldehydes, but no change is observed with ketones
134
free radical
very reactive atom or molecule that has a single unpaired electron
135
free-radical substitution
the reaction in which halogen atoms substitude for hydrogen atoms in alkanes. the mechanism involves steps in which reactive free radicals are produced (initiation), regenerated (propagation) and consumed (termination)
136
functional group
an atom or group of atoms in an organic molecule that determine the characteristic reactions of a homologous series
137
general formula
a formula that represents a homologous series of compounds using letters and numbers;e.g. the general formula for alkanes is CnH2n+2. by substituting a number for n in the general formula you get the molecular formula of a particular compound in that homologous series
138
giant molecular structure / giant covalent structure
structures having a three-dimensional network of covalent bonds throughout the whole structure
139
haglogens
group 17 elements
140
hydrocarbon
a compound made up of carbon and hydrogen only
141
hydrolysis
the breakdown of a compound by water, which is often speeded up by reacting with acid or alkali
142
hydroxynitrile
an organic compound containing both an OH and a CN group, e.g. 2-hydroxypropaneitrile, CH3CH(OH)CN
143
infra-red spectroscopy
a technique for identifying compounds based on the change in vibrations of particular atoms when infra-red radiation of specific frequencies is absorbed
144
initiation step
the first step in the mechanism of free-radical substitution of alkanes by halogens. it involves the breaking of the halogen-halogen bond by UV light from the Sun
145
metalloid
elements that have a low electrical conductivity at room temperature but whose conductivity increases with increasing temperature. ________ are found in a diagonal band running from the top left to nearly the bottom right of the p-block in the Periodic Table
146
monomer
a small, reactive molecule that reacts to make long-chain molecules called polymers
147
nanotechnology
the design and production of machines that are so small we measure them in nanometres (nm), where 1 nm = 1*10^-19 m
148
nucleophile
species that can act as a donor of a pair of electrons
149
nucleophilic addition
the mechanism of the reaction in which a nucleophile attacks the carbon atom in a carbonyl group and adds across the C=O bond,e.g. aldehydes or ketones reacting with hydrogen cyanide
150
optical isomers
stereoisomers that exist as two non-superimposable mirror images
151
periodicity
the repeating patterns in the physical and chemiscal properties of the elements across the periods of the Periodic Table
152
polymer
a long-chain molecule made up of many repeating units
153
primary alcohol
an alcohol in which the carbon atom bonded to the OH group is attached to one other carbon atom (or alkyl group)
154
propagation step
a step in a free radical mechanism in which the radicals formed can then attack reactant molecules generating more free-radicals, and so on.
155
secondary alcohol
an alcohol in which the carbon atom bonded to the OH group is attached to two other carbon atoms (or alkyl group)
156
saturated hydrocarbons
compounds of hydrogen and carbon only in which the carbon-carbon bonds are all single covalent bonds, resulting in the maximum number of hydrogen atoms in their molecules.
157
Sn1 mechanism
the steps in a nucleophilic substitution reaction in which the rate of the reaction (which is determined by the slow step in the mechanism) involves only the organic reactant, e.g. in hydrolysis of a tertiary halogenoalkane
158
Sn2 mechanism
the steps in a nucleophilic substitution reaction in which the rate of the reaction (which is determined by the slow step in the mechanism) involves two reacting species, e.g. in the hydrolysis of a primary halogenoalkane
159
solute
a substance that is dissolved in a solution
160
stereoisomers
compounds whose molecules have the same atoms bonded to each other (same structural formular) but with different arrangement of atoms in space
161
structural isomers
compounds with the same molecular formula but different structural formulae
162
substitution
a reaction that involves the replacement of one atom, or group of atoms, by another
163
termination step
the final step in a free-radical mechanism in which two free radicals react together to form a molecule
164
tertiary alcohol
an alcohol in which the carbon atom bonded to the OH group is attached to three other carbon atoms (or alkyl group)
165
Tollen's reagent
an aqueous solution of silver nitrate in excess ammonia solution, sometimes called ammoniacal silver nitrate solution. it is used to distinguish between aldehydes and ketones. it gives a positive 'silver mirror'test when warmed with aldehydes, but no change is observed with ketones
166
unsaturated hydrocarbons
compounds of hydrogen and carbon only whose molecules contain carbon-carbon double bonds (or triple bonds)
