Chemistry definitions Flashcards
Key definitions for AS chemistry
1
Q
DEFINE: Relative Isotopic Mass
A
The mass of an atom of a isotope compared with one-twelfth the mass of a carbon-12 atom
2
Q
DEFINE: Relative Atomic Mass
A
The weighted mean mass of an atom of a element compared with one-twelfth the mass of an carbon-12 atom
3
Q
DEFINE: Relative molecular mass
A
The weighted mean mass of a molecule compared to the mass of one-twelfth the mass of an carbon-12 atom
4
Q
DEFINE: Relative Formula Mass
A
The weighted mean mass of a formula unit compared with one-twelfth the mass of a carbon-12 atom
5
Q
DEFINE: Avogrado Constant
A
The number of atoms per mole of the carbon-12 isotope (6.02 x10^23)
6
Q
DEFINE: A Mole
A
A mole is the amount of substance containing as many particles as there are carbon atoms in 12g of the carbon-12 isotope
7
Q
DEFINE: Molar mass
A
Mass per mole of a substance
8
Q
DEFINE: Empirical formula
A
The simplest whole number ratio of atoms of each element present in a compound
9
Q
DEFINE: Concentration
A
IS the amount of solute in mol dissolved per dm^3 of solution
10
Q
DEFINE: Species
A
Any type of particle that takes part in a chemical reaction
11
Q
DEFINE: Acid
A
A acid is a species that is a proton donor.
12
Q
DEFINE: Base
A
A base is a species that is a proton acceptor
13
Q
DEFINE: Alkali
A
A type of base that dissolves in water forming OH- (hydroxide ions)
14
Q
DEFINE: Salt
A
any chemical compound formed from a acid when a H+ ion from the acid has been replaced by a metal/positive ion
15
Q
DEFINE: Cation
A
a postively charged ion
16
Q
DEFINE: Anion
A
Negatively charged ion
17
Q
DEFINE: Water of crystallisation
A
It refers to the water molecules that form an essential part if the crystalline structure of a compound
18
Q
DEFINE: Hydrated
A
crystalline compound containing water molecules
19
Q
DEFINE: Anhydrous
A
substance containing no water molecules
20
Q
DEFINE: Oxdiation number
A
measure of the number of electrons that a atom uses to bond with another element
21
Q
DEFINE: Oxidation
A
Loss of electrons or increase in Oxdiation number
22
Q
DEFINE: Reductions
A
gain of electrons or decrease in oxidation number
23
Q
DEFINE: Redox reaction
A
a reaction is which both reduction and oxidation take place
24
Q
DEFINE: Reducing Agent
A
a reagent that reduces another species ( it adds a electron to )
25
DEFINE: Oxidising agent
a reagent that oxidises (takes a electron from) anther species
26
DEFINE: FIRST IE
energy required to remove one electron from each atom in one mol of gaseous atoms to form one mol of gaseous 1+ ions
27
DEFINE: Electron shielding
repulsion between electrons in different inner shells
28
DEFINE: Shelll
A shell is a group of atomic orbitals with the same principal quantum number, n. (Shell no.)
29
DEFINE: Atomic Orbital
region within a atom that can hold up to 2 electrons with opposite spins
30
DEFINE: Sub-shell
a group of same type of atomic orbitals (s,p,d or f) within a shell
31
DEFINE: Electron Configuration
the arrangements of electrons in a atom
32
DEFINE: Ionic bond
electrostatic attraction between oppositely charged ions
33
DEFINE: Giant Ionic Lattice
3D structure of oppositely charger ions held together by strong ionic bonds
34
DEFINE: Covalent bond
Bond formed by a shared pair of electrons
35
DEFINE: Lone pair
outer she'll pair of electrons not involved in chemical bonding
36
DEFINE: DATIVE COVALENT BOND
Shared pair of electrons which has even provided by one of the bonding atoms only
37
DEFINE: Electronegativity
Measure of the attraction of a bonded atom for the pair of electrons in the covalent bond
38
DEFINE: Permanent Dipole
Small charge difference across a bond that results from a difference in electronegativitys in the atoms
39
DEFINE: Polar Covalent Bond
Permanent dipole
40
DEFINE: Polar molecule
A molecule that has an overall dipole when you take into accounts any dipoles across bonds
41
DEFINE: Intermolecular Force
Attractive force between neighbouring molecules
42
DEFINE: Permanent dipole-dipole force
weak attractive force between permanent dipoles in neighbouring polar molecules
43
DEFINE: Van der Waal's
Attractive forces between induced dipoles in neighbouring molecules
44
DEFINE: Hydrogen bond
Strong dipole-dipole attraction between a electron-deficient hydrogen atom on one molecule and a lone pair of electrons on a highly electronegative atom on a different molecule
45
DEFINE: Metallic Bonding
Electrostatic attraction between positive metal ions and delocalised electrons
46
DEFINE: Delocalised Electrons
Electrons that are shared between more than two atoms
47
DEFINE: Giant Metallic Lattice
A 3D structure of positive metal ions and delocalised electrons bonded together by strong metallic bonds
48
DEFINE: Giant Covalent Lattice
3D Structure of atoms bonded together by strong covalent bonds
49
DEFINE: Simple molecular lattice
3D structure of molecules bonded together by weak intermolecular forces
50
DEFINE: Periodicity
Regular periodic variation of properties of elements with atomic number and position in the periodic table
51
DEFINE: Thermal Decomposition
Breaking up of a chemical substance with heat into at least two chemical substances
52
DEFINE: Displacement reaction
Reaction in which a more reactive element displaces a less-reactive element from an aqueous solution of the latter's ions
53
DEFINE: Disproportionation
The oxidation and reduction of the same element in a redox reactions
54
DEFINE: Precipitation Reaction
Formation of a solid from a solution during a chemical reaction
55
DEFINE: Hydrocarbon
A organic compound containing only a carbon and hydrogen
56
DEFINE: Saturated Hydrocarbon
hydrocarbon with single bonds only
57
DEFINE: Unsaturated Hydrocarbon
Hydrocarbon containing carbon to carbon multiple bonds
58
DEFINE: Aliphatic Hydrocarbon
Hydrocarbon with carbon atoms joined together in straight or branched chains
59
DEFINE: Alicyclic Hydrocarbon
Hydrocarbon with carbon atoms joined together in a ring structure
60
DEFINE: Functional Group
Part of the organic molecule responsible for the chemical reactions
61
DEFINE: Homologous Series
Series of organic compounds with the same functional group but each successive member differing by ch2
62
DEFINE: Nomenclature
System of naming compounds
63
DEFINE: Alkyl group
A alkane with a hydrogen atom removed
64
DEFINE: General Formula
Simplest algebraic formula of a member of a homologous series. e.g CnH2n+2
65
DEFINE: Displayed formula
Shows the relative positioning of all the atoms in a molecule and the bonds between them
66
DEFINE: Structural Formula
Shows the minimal detail of the arrangement of atoms in a molecule
67
DEFINE: Skeletal Formula
Simplified organic formula, with hydrogen atoms removed from alkyl chains, leaving just the carbon skeleton and associated functional groups
68
DEFINE: Stereoisomers
Compounds with the same structural formula but different arrangements of the atoms in space
69
DEFINE: Structural Isomers
Molecules with the same molecular formula but with different structural formulas
70
DEFINE: Homolytic Fission
Breaking of a covalent bond with one of the electron in the bond going to each atom forming two radicals
71
DEFINE: Radical
Species with an unpaired electron
72
DEFINE: Heterolytic Fission
Breaking of a covalent bond with both of the bonded electrons going to one atoms forming a cation and an anion
73
DEFINE: Nucleophile
An atom or group that is attracted to an electron deficient centre where it donates a pair of electrons to form a covalent bond
74
DEFINE: Electrophile
An atom or group that is attracted to an electron rich centre where it accepts a pair of electrons to form a new covalent bond
75
DEFINE: Fractional Distillation
Separation of the components in a liquid mixture into fractions which differ in boiling point.
76
DEFINE: Cracking
Cracking is the breakdown of long-chained saturated hydrocarbons to form a mixture of shorter chained alkanes and alkenes.
77
DEFINE: Catalyst
Substance that increases the rate of reaction without being used up in the process
78
DEFINE: Isomerisation
Converting unbranched alkanes into branched alkanes
79
DEFINE: Reforming
Converting aliphatic (straight/branched alkanes) into cyclic or aromatic hydrocarbons
80
DEFINE: Radical Substitution
Type of substitution reaction in which a radical replaces a different atom or group of atoms
81
DEFINE: Mechanism
Sequence of steps showing the path an electron takes in a reactions
82
DEFINE: Initiation
First step in a radical substitution in which free radicals are generated using UV radiation/ light
83
DEFINE: Propagation
Two repeated steps in radical substitution which build up the products in chemical chain reaction
84
DEFINE: Termination
Step at the end of a radical substitution where two radicals combine to form a molecule
85
DEFINE: Pi-Bond
The reactive part of a double bond, formed above and below the plane of bonded atoms by sideways overlap of p orbitals
86
DEFINE: Electrophilic Addition
Type of addition reaction in which an electrophile is attracted to a electron rich centre or atom where it accepts a pair of electrons to form a covalent bond
87
DEFINE: Carbocation
Organic ion in which the carbon atom has a positive charge
88
DEFINE: Curly Arrow
Symbol used to reaction mechanisms to show the movement of a electron pair in the breaking or formation of a covalent bond
89
DEFINE: Polymer
Long chain molecular built up of monomer units
90
DEFINE: Monomer
Small molecule that combines with many other monomers to form a polymer
91
DEFINE: Repeat unit
Specific arrangement of atoms that occurs in the structure over and over again. They are shown in square brackets with a n outside them
92
DEFINE: Volatility
Ease of which a liquid turns into a gas.
93
DEFINE: Reflux
Continual boiling and condensing of a reaction mixture to ensure the reaction takes place without the contents of the boiling flask boiling dry
94
DEFINE: Esterification
Reaction of a alcohol and carboxylic acid to produce a ester and water
95
DEFINE: Dehydration
An elimination reaction in which water in removed from a saturated molecule to make a unsaturated molecule
96
DEFINE: Hydrolysis
Reaction with water or aqueous hydroxide ions that breaks a chemical compound into two compounds
97
DEFINE: Nucleophilic Substitution
Type of substitution reaction in which a nucleophile is attracted to a electron deficient centre where it donates a pair of electrons to form a covalent bond
98
DEFINE: Limiting Reagent
Substance in a chemical reaction that runs out first
99
DEFINE: Molecular Ion, M+
Postive ion formed in mass spec when a molecule loses an electron
100
DEFINE: Fragmentation
Process in mass spec that causes a positive ion to spilt into pieces
101
DEFINE: Enthalpy
Is the heat content that is stored in a chemical system
102
DEFINE: Exothermic
Reaction in which the enthalpy of the products is smaller than the enthalpy of the reactants, resulting in heat loss to the surroundings
103
DEFINE: Endothermic
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
104
DEFINE: Activation energy
Minimum energy required to start a reaction by the breaking of bonds
105
DEFINE: Standard Conditions
Pressure of 100 kPa ( 1 atm), a stated temperature usually 289K, (25ºC) and a concentration of 1.0 mol/dm3
106
DEFINE: Standard State
Physical state of a substance under standard conditions
107
DEFINE: Standard Enthalpy Change of Combustion
Enthalpy change that takes place when one mole of substance reacts completely with oxygen under standard conditions, all reactants and products being in their stander states.
108
DEFINE: Standard Enthalpy Change of Formation
Enthalpy change that takes place when one mole of substance is formed form its constituent elements in their standard states under standard conditions
109
DEFINE: Bond Enthalpy
The enthalpy change that takes places when breaking by homolytic fission 1 mol of a given bond in the molecules of a gaseous species
110
DEFINE: Average Bond Enthalpy
Average enthalpy change that takes place when breaking by homolytic fission 1 mol of a given type of bond in the molecules of a gaseous species
111
DEFINE: Hess' law
It states that if a reaction can 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
112
DEFINE: Heterogenous Catalysts
The catalysis of a reaction in which the catalyst and reactants are a different physical state from the reactants
113
DEFINE: Homogeneous Catalysts
Catalysis of a reaction in which the catalyst and reactants are in the same physical state
