Definitions Flashcards
(129 cards)
1
Q
Acid
A
A species that releases H+ ions in aqueous solution
2
Q
Activation Energy
A
The minimum energy required to start a reaction by the breaking of bonds
3
Q
actual yield
A
the amount of product obtained from a reaction
4
Q
addition polymerisation
A
a formation of a very long molecular chain, by repeated addition of many unsaturated alkenes
5
Q
addition reaction
A
a reaction in which a reactant is added to an unsaturated molecule to make a one saturated molecule
6
Q
adsorption
A
the process that occurs when a gas or a liquid or solute is held to the surface of a solid
7
Q
alicyclic
A
containing carbon atoms joined together in a ring that is not aromatic
8
Q
aliphatic
A
containing carbon atoms joined together in branched (straight) or branched chains
9
Q
alkali
A
a type of base that dissolves in water to release hydroxide ions
10
Q
alkanes
A
the hydrocarbon homologous series with the general formula CnH2n+2
11
Q
alkenes
A
the hydrocarbon homologous series with one double carbon-to-carbon bonds and the general formula CnH2n
12
Q
alkyl group
A
a side chain formed by removing a hydrogen atom removed from and alkane parent chain. Amy alkyl group is often show as ‘R’
13
Q
alkynes
A
the hydrocarbon homologous series with one triple carbon-to-carbon bonds and the general formula CnH2n-2
14
Q
amount of substance (n)
A
the quantity whose unit of the mole. chemists use amount of substance as a means of counting atoms
15
Q
anhydrous
A
containing no water molecules
16
Q
anion
A
a negatively charged ion with more electrons than protons
17
Q
aromatic
A
containing one or more benzene rings
18
Q
atom economy
A
(molar mass of products/total molar mass)*100%
19
Q
atomic number (z)
A
the number of protons in the nucleus of an atom(proton number)
20
Q
atomic orbital
A
a region around the nucleus that can hold up to two electrons, with opposite spins
21
Q
average bond enthalpy
A
the average enthalpy change that takes place when breaking by homolytic fission one mole of a given type of bond in the molecules of a gaseous species
22
Q
avogadro constant
A
6.022*10^23 mol^-1, the number of atoms per mole of carbon 12
23
Q
avogadro’s hypothesis
A
equal volumes of gases at the same temperature and pressure contain the same number of molecules
24
Q
base
A
a compound that neutralises an acid to form a salt
25
binary compound
a compound containing two elements only
26
bond angle
the angle between two bonds at an atom
27
bonded pair
a pair of electrons shared between to make a covalent bond
28
carbocation
an ion that contains a positively charged carbon atom
29
catalyst
a substance that increases the rate of a chemical reaction without being used up in the process. A catalyst provides an alternative route for the reaction with a lower activation energy
30
cation
a positively charged ion with fewer electrons than protons
31
chain reaction
a reaction in which the propagation steps release new radicals that continue the reaction
32
cis-trans isomerism
a special type of E/Z isomerism in which there are two non hydrogen groups and two hydrogen atoms around the C-C double bond - the cis isomer (Z isomer) has hydrogen atoms on each carbon on the same side, whilst the trans isomer (E isomer) has hydrogen atoms on each carbon on different sides
33
closed system
a system isolated from its surroundings
34
collision theory
two reacting particles must collide for a reaction to occur and must be in the correct orientation and have sufficient energy to overcome the activation energy of the reaction
35
coordinate bond
a shared pair of electrons in which the bonded pair has been provided by one of the bonding atoms only. Also called a dative covalent bond.
36
covalent bonding
the strong electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms
37
dative covalent bond
a shared pair of electrons in which the bonded pair has been provided by one of the bonding atoms only; also called a coordinate bond
38
dehydration
an elimination reaction in which water is removed from a saturated molecule to make an unsaturated moelcule
39
delocalised electrons
electrons that are shared between more than two atoms
40
desorption
release of an absorbed substance from a surface
41
dipole
a separation in electrical charge so that one atom of a polar covalent bond, has a small positive charge delta+ and the other has a small negative charge delta-
42
dipole-dipole force
an attractive force between permanent dipoles in neighbouring polar moleculs
43
displacement reaction
a reaction in which a more reactive element displaces a less reactive element from an aqueous solution of its ions
44
displayed formula
a formula that shows the relative positioning of all atoms in a molecule and the bonds between them
45
disproportionation
a redox reaction in which an element is both oxidised and reduced
46
dynamic equilibrium
the equilibrium that exists in a closed system when the rate of teh forward reaction is equal to the rate of the reverse reaction and concentrations do not change
47
E/Z isomerism
a type of stereosiomerism in which different groups attached to each carbon of a C=C double bond may be arranged differently in space because of the restricted roatation of the C=C bond
48
electron configuration
a shorthand method for showing how electrons occupy sub-shells in an atom
49
elecgtronegativity
a measure of the attraction of a bonded atom for the pair of electrons in a covalent bond
50
electrophile
an atom or group of atoms that is attracted to an electron-rich centre, where it acceepts a pair of electrons
51
electrophilic addition
an adition reaction in which the first step is attack by an electrophile on a region of high electron density
52
elimination reaction
the removal of a molecule from a saturated molecule to make an unsaturated molecule
53
empirical formula
a formula that shows the simplest whole number ratio of atoms of each element present in a compound
54
end point
the point in a titration where the indicator changes colour; the end point indicates when the reaction is just complete
55
endothermic reaction
a reaction in which the enthalpy of the products is greater than the enthalpy of the reactants, resulting in heat being taken in from the surroundings (deltaH is positive)
56
enthalpy
the heat content that is stored in a chemical system
57
enthalpy charge (deltaH)
difference in enthalpy between reactants an products in a reaction
58
enthalpy cycle
a diagram showing alternative routes between reactants and products which allpws the indirec determination of an enthalpy change from other known enthalpy changes using hess' law
59
enthalpy profile diagram
a diagram for a reaction to compare the enthalpy of the reactants with the enthalpy of the products
60
equilibrium constant
a measure of the position of equilibrium; the magnitude of an equilibrium constant indicates whether there are more reactants or more products in an equilibrium system.
61
exothermic reaction
a reaction in which the enthalpy of the products is smaller than the enthalpy of the reactants resulting in heat loss to the surroundings (deltaH negative)
62
fingerprint region
an area of an infrared spectrum below 1500cm^-1 that gives a characteristic pattern for different compounds
63
first ionisation energy
the energy required to remove one electron from each atom in one mole of gaseous atoms of an element to form one mole of gaseous 1+ ions
64
fractional distillation
the separation of components in a liquid mixture by their different boiling points into fractions with different composition
65
fragment ions
ions formed from the breakdown of the molecular ion in a mass spectrometer
66
fragmentation
the process in mass spectrometry that cause a positive ion to split into smaller pieces, one of which is a positive fragment ion
67
functional group
the part of the organic molecule responsible for its chemical reaction
68
general formula
the simplest algebraic formula of a member of a homologous series. For example the general formula of alkanes is CnH2n+2
69
giant covalent lattice
a three dimensional structure of atoms, bonded together by strong covalent bonds
70
giant ionic lattice
a three dimensional structure of oppositely charged ions bonded together by strong ionic bonds
71
giant metallic lattice
a three dimensional structure of positive ions and delocalised electrons, bonded together by strong metallic bonds
72
group
a vertical column in the periodic table. elements in a group have similar chemical properties and their atoms have the same number of outer shell electrons
73
hess' law
in a reaction take place by more than one route and the initial and final conditions are the same, the total enthalpy change is the same for each route
74
heterogeneous catalysis
a reaction in which the catalyst has a different physical state from the reactants; frequently reactants are gases whilst the catalyst is solid
75
heterolytic fission
the breaking of a covalent bond with both of the bonded electrons going to each atom, forming a cation (positive ion) and an ion (negative ion)
76
homogeneous catalysis
a reaction in which the catalyst and reactants are in the same physical state, which is most frequently the aqueous or gaseous state
77
homologous series
a series of organic compounds with the same functional but with each successive member differing by CH2
78
homolytic fission
the breaking of a covalent bond with one of the bonded electrons going to each atom, forming two radicals
79
hydrated
a crystalline compound containing water molecules
80
hydrocarbon
a compound containing carbon and hydrogen only
81
hydrogen bond
a strong dipole-dipole attraction between an electron-deficient hydrogen atom of -NH, -OH, or HF on one molecule and lone pair of electrons on a highly electronegative atom containing N, O or F on a different molecule
82
hydrolysis
a reaction with water that breaks a chemical compound into two compounds, the H and OH in a water molecule becomes incorporated into the two compounds
83
induced dipole-dipole interaction
attractive forces between induced dipoles in different molecules; also called london forces
84
initiation
the first stage in a radical reaction in which radical starts when a covalent bond is broken by homolytic fission of a covalent bond
85
intermediate
a species formed during a reaction that reacts further and is not present in the final products
86
intermolecular forces
an attractive force between molecules. Intermolecular forces can be london forces, permanent dipole-dipole interactions or hydrogen bonding
87
ion
a positively or negatively charged atom or a (covalently bonded) group of atoms (a polyatomic ion), where the number of electrons is different from the number of protons
88
ionic bonding
the electrostatic attraction between positive and negative ions
89
isotope
atoms of the same element with different numbers of neutrons and different masses
90
le chatelier's principle
when a system in dynamic equilibrium is subjected to a external change, the system readjusts itself to minimise the effect of the change and to restore equilibrium
91
limiting reagent
the reactant that is not in excess which will be used up first and stop the reaction
92
london forces
attractive forces between induced dipoles in different molecules; also known as induced dipole-dipole interactions
93
lone pair
an outer shell pair of electrons that is not involved in chemical bonding
94
mass number A
the sum of the number of protons and neutrons in the nucleus; also known as nucleon number
95
metallic bonding
the electrostatic attraction between positive metal ions and delocalised electrons
96
concentration
the amount of solute, in mole, dissolved in 1 dm^3 of solution
97
molar gas volume
the volume per mole of gas molecules at a stated temperature and pressure
98
molar mass
the mass per mole of a substance, in units of gmol^-1
99
mole
the amount of any substance containing many elementary particles as there are carbon atoms in exactly 12g of the carbon-12 isotope
100
molecular formula
a formula that shows the number and type of atoms of each element present in a molecule
101
molecular ion
the positive ion formed in mass spectrometry when a molecule loses an electron
102
molecule
the smallest part of a covalent compound that can exist while retaining its chemical identity consisting of two or more atoms covalently bonded together
103
monomer
a small molecule that combines with many other monomers to form a polymer
104
neutralisation
the reaction between an acid and a base to produce a salt
105
nomencalture
a system of naming compounds
106
non polar
with no charge seperation across a bond or in a molecule
107
nucleon number
the number of protons and neutrons in an atom
108
nucleophile
an atom or group of atoms that is attracted to an electron- deficient carbon atom where it donates a pair of electrons to form a new covalent bond
109
nucleophilic substitution
a reaction in which a nucleophile is attracted to an electron deficient carbon atom and replaces an atom or group of atoms on it
110
oxidation
loss of electrons or an increase in oxidation number
111
oxidation number
a measure of the number of electrons that na atom uses to bond with atoms of another element. oxidation number are derived from a set of rules
112
oxidation state
the oxidation number
113
oxidising agent
a reagent that oxidises another species
114
pi bond
a bond formed by the sideways overlap of two p orbitals, containing two electrons and with the electron density concentrated above and below the line joining the nuclei of the bonding atoms
115
partial dissociation
the splitting of some of a species in solution into aqueous ions
116
pauling electronegativity value
a value assigned as a a measure of the relative attraction of a bonded atom for the pair of electrons in a covalent bond
117
percentage yield
actual yield of a product/theoretical yield of a product *100%
118
periodicity
a repeating trend in properties of the elements across each period of the periodic table
119
period
a horizontal row of elements in the periodic table. elements show trend in properties across a period
120
permanent dipole
a small charge difference that does not change across a bond, with positive and negative partial changes on the bonded atoms: the result of the bonded atoms having different electronegatives
121
permanent dipole-dipole interactions
attractive forces between the permanent dipoles in different molecules
122
polar molecule
a molecule with an overall dipole, having taken into account any dipoles across bonds and the shape of the molecule
123
polar covalent bond
a bond with a permanent dipole, having positive and negative partial changes on the bonded atoms
124
polyatomic ion
an ion containing more than one atom
125
polymer
an large molecule formed from many thousands of repeat units of smaller molecules known as monomers
126
position of equilibrium
the relative quantities of reactants and products, indicating the extent of a reversible reaction at equilibrium
127
primary
on a carbon atom at the end of a chain
128
priamry alcohol
an alcohol in which the -OH. group is attached to a carbon atom that is attached to two or three hydrogen atoms
129
principal quantum number
a number representing the relative overall energy of each orbital, which increases with distance from the nucleus. the sets of orbitals with the same n-value are referred to as electron shells or energy levels
