Chemistry definitions

HideShow resource information
  • Created by: Bethany33
  • Created on: 18-04-15 10:45
Isotope
atoms of the same element with different numbers of neutrons
1 of 144
Atomic Number
The number of protons in the nucleus of an atom
2 of 144
Mass number
The number of particles(protons and neutrons) in the nucleus
3 of 144
Ion
a positively or negatively charged atom or (covalently bonded) group of atoms(a molecular ion)
4 of 144
Relative Isotopic mass
The mass of an atom of an isotope compared with one-twelfth of the mass of an atom of carbon-12
5 of 144
Relative atomic mass
the weighted mean mass of an atom of an element compared with one-twelfth the mass of an atom of carbon-12
6 of 144
Relative molecular mass
The weighted mean mass of a molecule compared with the mass of an atom of carbon-12
7 of 144
Relative formula mass
the weighted mean mass of a formula unit compared with one-twelfth the mass of an atom of carbon-12
8 of 144
Avogadro constant
the number of atoms per mole of the carbon-12 isotope (6.02 x 10^23 mol^-1)
9 of 144
Mole
the amount of any substance containing as many particles as there are carbon atoms in exactly 12g of the carbon-12 isotope
10 of 144
Molar Mass
The mass per mole or a substance (grams per mole)
11 of 144
The empirical formula
The simplest whole number ratio of atoms of each element present in a compound
12 of 144
Molecule
small group of atoms help together by covalent bonds
13 of 144
Molecular Formula
The actual number of atoms of each element in a molecule
14 of 144
Molar Volume
the volume per mole of a gas. (dm^3 per mole) at RTP this is 24.0 dm3mol-1.
15 of 144
Concentration
the amount of solute dissolved in moles per dm^3 of solution
16 of 144
Standard Solution
A solution of known concentration
17 of 144
Species
any type of particle that takes place in a chemical reaction
18 of 144
Stoichiometry
The molar relationship between relative quantities of substances taking part in a reaction
19 of 144
Acid
A species that is a proton donor
20 of 144
Base
A species that is a proton acceptor
21 of 144
Alkali
A type of base that dissolves in water to form hydroxide ions (OH-)
22 of 144
Salt
A chemical compound formed from an acid when a H+ ion is replaced by a metal cation or other positive ion(NH4+)
23 of 144
Cation
A positively charged ion
24 of 144
Anion
A negatively charged ion
25 of 144
Hydrated
A crystalline compound containing water
26 of 144
Anhydrous
A substance that contains no water molecules
27 of 144
Water of crystillisation
water molecules that form an essential part of the crystalline structure of a compound
28 of 144
Oxidation Number
A measure of the number of electrons that an atom uses to bond with atoms of another element. Oxidation numbers are derived from a set of rules.
29 of 144
Oxidation
Loss of electrons or an increased oxidation number
30 of 144
Reduction
Gain of electrons, or a reduced oxidation number
31 of 144
Redox reaction
a reaction in which both oxidation and reduction take place
32 of 144
A reducing agent
A reagent that reduces(adds electrons to) another species
33 of 144
An oxidising agent
A reagent which oxidises(removes electrons from) a species
34 of 144
First ionisation energy
The energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous +1 ions
35 of 144
Electron shielding
The repulsion between electrons in different inner shells. Shielding reduced the net attractive force of the nucleus on the outer-shell electrons.
36 of 144
Successive ionisation energies
A measure of the energy required to remove each electron in turn (ie Second ionisation energy = the energy required to remove one electron from each atom of a mole of gaseous +1 ions to form one mole of gaseous +2 ions)
37 of 144
Shell
A group of atomic orbitals with the same principal quantum number, n, also known as a main energy level
38 of 144
Principal quantum number (n)
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 values are referred to as shells or energy levels.
39 of 144
Atomic orbital
A region within an atom which can hold up to two electrons with opposite spins
40 of 144
Sub-shell
A group of the same type of atomic orbitals(s, p, d, f) within a shell
41 of 144
Electron configuration
The arrangement of electrons in an atom
42 of 144
Compound
A substance formed from two or more chemically bonded elements in a fixed ratio, usually shown by a chemical formula
43 of 144
Ionic bond
The electrostatic attraction between oppositely charged ions
44 of 144
Giant Ionic Lattice
Three dimensional structure of oppositely charged ions, held together by strong ionic bonds
45 of 144
Group
A vertical column in the periodic table (same number of outer-shell electrons and similar properties)
46 of 144
Covalent Bond
A shared pair of electrons
47 of 144
Lone pair
An outer-shell pair of electrons which are not involved in chemical bonding
48 of 144
Dative covalent bond
A shared pair of electrons which has been provided by one of the bonding atoms only
49 of 144
Electronegativity
The measure of attraction of a bonded element for the pair of electrons in a covalent bond
50 of 144
Permanent dipole
A small charge difference across a bond that results from a different in electronegtivity of the bonded atoms
51 of 144
Polar covalent bond
Has a permanent dipole
52 of 144
Polar molecule
Has an overall dipole when you take into account any dipoles across the bonds
53 of 144
Intermolecular force
attractive force between neighbouring molecules
54 of 144
Permanent dipole-dipole
weak attractive force between permanent dipoles in neighbouring polar molecules
55 of 144
Van der Waal's
attractive forces between induced dipoles
56 of 144
Hydrogen bond
A strong dipole dipole attraction between and electron deficient hydrogen atom on one molecule and a lone pair on a highly electronegative atom on a different molecule
57 of 144
Metallic Bonding
The electrostatic attraction between positive metal ions and delocalised electrons
58 of 144
Delocalised electrons
shared between more than two atoms
59 of 144
Giant Metallic Lattice
Three dimensional structure of metal cations and delocalised electrons held together by metallic bonding
60 of 144
Simple molecular lattice
Three-dimensional structure of molecules bonded by weak intermolecular forces
61 of 144
Giant covalent lattice
Three-dimensional structure of atoms help together by strong, covalent bonds.
62 of 144
Period
A horizontal row in the periodic table. Elements show trends in properties across a period.
63 of 144
Periodicity
regular periodic variation of properties of elements with atomic number and position in periodic table
64 of 144
Thermal Decomposition
The breaking up of a chemical substance with heat into at least two chemical substances
65 of 144
Displacement reaction
A reaction in which a more reactive element replaces a less reactive element from an aqueous solution of the latter's ions
66 of 144
Disproportionation
An oxidation and a reduction of the same element in a redox reaction
67 of 144
Precipitation reaction
The formation of a solid from a solution during a chemical reaction. Often formed when two aqueous solutions are mixed together
68 of 144
Hydrocarbon
Organic compound containing carbon and hydrogen only
69 of 144
Saturated hydrocarbon
Hydrocarbon with single bonds only
70 of 144
Unsaturated hydrocarbon
Hydrocarbon containing carbon to carbon multiple bonds
71 of 144
Aliphatic hydrocarbon
Hydrocarbon with carbon atoms joined together in straight or branched chains
72 of 144
Alicyclic hydrocarbon
Hydrocarbon with carbon atoms joined in a ring structure
73 of 144
Functional group
The part of the organic molecule responsible for its chemical reactions
74 of 144
Homologous series
A series of organic compounds with the same functional group but with each successive number differing by CH2
75 of 144
Alkanes
The homologous series with the genera formula CnH2n+2
76 of 144
Nomenclature
A system of naming compounds
77 of 144
Alkyl group
An alkane with a hydrogen atom removed, often shown as R
78 of 144
General formula
The simplest algebraic formula of a member of the homologous series
79 of 144
Displayed formula
Shows the relative positioning of all the atoms in a molecule and the bonds between them
80 of 144
Structural formula
The minimum detail for the arrangement of atoms in a molecule
81 of 144
Skeletal formula
Simplified organic formula, hydrogens removed from alkly chains, leaving just a carbon skeleton and functional groups
82 of 144
Structural isomers
Molecules with the same molecular formula but different structural arrangements of atoms
83 of 144
Sterioisomers
molecules with the same structural formula but different arrangement of atoms in space
84 of 144
E/Z isomerism
Type of sterioisomerism in which different groups attached to each carbon of a C=C double bond may be arranged differently in space because of the restricted rotation of the C=C double bond
85 of 144
Cis-Tans isomerism
Special type of E/Z in which there is a non-hydrogen group and a hydrogen on each C in a C=C: The cis(Z) has the H atoms on each carbon on the same side : trans(E) has the H atoms on carbons on the opposite sides
86 of 144
Homolytic fission
The breaking of a covalent bond with one of the electrons going to each atom, forming two radicals
87 of 144
Radical
A species with an unpaired electron
88 of 144
Heterolytic fission
The breaking of a covalent bond with both of the electrons going to only one of the atoms, forming an anion and a cation
89 of 144
Nucleophile
An atom (or group of atoms) that is attracted to an electron deficient centre or atom where it donates a pair of electrons to form a new covalent bond
90 of 144
Electrophile
An atom (or group of atoms) that is attracted to an electron-rich centre or atom, it accept a pair of electrons to form a new covalent bond
91 of 144
Addition reaction
A reactant is added to an unsaturated molecule to form a saturated molecule
92 of 144
Substitution reaction
An atom or group of atoms is replaced by a different atom or group of atoms
93 of 144
Elimination reaction
Removal of a molecule from a saturated molecule to form an unsaturated molecule
94 of 144
Fractional distillation
The separation of components in a liquid mixture into fractions which differ in boiling point by means of distillation, often using a fractioning column
95 of 144
Cracking
The breaking down of long chained saturated hydrocarbons to form a mixture of shorter alkanes and alkenes
96 of 144
Catalyst
A substance that increases the rate of a chemical reaction without being used up in the reaction itself
97 of 144
Radical Substitution
A type of substitution reaction in which a radical replaces a different atom or group of atoms
98 of 144
Mechanism
A sequence of steps showing the path taken by electrons in a reaction
99 of 144
Initiation
The first step in radical substitution in which free radicals are generated by UV radiation
100 of 144
Propagation
The two repeated steps in radical substitution which build up the products in a chain reaction
101 of 144
Termination
The last step of radical substitution when two radicals combine to form a molecule
102 of 144
Pi-bond
The reactive part of a double bond formed above and below the plane of bonded atoms by sideways overlap of p orbitals
103 of 144
Electrophilic addition
A type of addition reaction where an electrophile is attracted to an electron-rich centre or atom, where it accepts a pair of electrons forming a new covalent bond
104 of 144
Carbocation
An organic ion in which a carbon atom has a positive charge
105 of 144
Curly arrow
Symbol used in mechanism reactions to show the movement of electrons in the breaking or forming of a covalent bond
106 of 144
Polymer
A molecular chain made up from monomer units
107 of 144
Monomer
A small molecule which combines with other monomers to form a polymer
108 of 144
Addition polymerisation
Unsaturated alkene monomers add onto a growing polymer chain one at a time to form a long polymer chain
109 of 144
Addition polymer
long molecular chain formed by repeated addition reactions of many unsaturated alkene molecules
110 of 144
Repeat unit
specific arrangement of atoms that occurs repeatedly in the structure. repeat units are in brackets outside of which lies the symbol n
111 of 144
Biodegradable material
A material broken down in the environment by living organisms
112 of 144
Volatility
The ease that a liquid turns into a gas
113 of 144
Reflux
The continual boiling and condensing of a reaction mixture to ensure the reaction takes place without the contents of the flask boiling dry
114 of 144
Esterfication
The reaction of an alcohol with a carboxylic acid to produce an ester and water
115 of 144
Dehydration
elimination reaction in which water is removed from a saturated molecule to make an unsaturated molecule
116 of 144
Hydrolysis
A reaction with water or aqueous hydroxide ions which breaks a chemical compound into two compounds
117 of 144
Nucleophilic substitution
a type of substitution reaction in which a nucleophile is attracted to an electron-deficient atom or centre, where it donates a pair of electrons to form a new covalent bond
118 of 144
Limiting Reagent
The substance in a chemical reaction that runs out first
119 of 144
Molecular ion
The positive ion formed in mass spectrometry when a molecule loses an electron
120 of 144
Fragmentation
The process in mass spectrometry which causes a positive ion to split into pieces, one of which is a positive fragment ion
121 of 144
Enthalpy
The heat content that is stored in a chemical system
122 of 144
Exothermic
A reaction in which the enthalpy of the product is smaller than that of the reactants, heat loss to the surroundings
123 of 144
Endothermic
A reaction where the enthalpy of the reactnts is lower than that of the products, heat is drawn in from the surroundings
124 of 144
Activation energy
The minimum energy required to start a reaction by the breaking of bonds
125 of 144
Standard conditions
100kPa, 298K, 1.0 mol dm^-3(for aqueous)
126 of 144
Standard state
Physical state of a substance under the standard conditions
127 of 144
Enthalpy change of reaction
The enthalpy change that accompanies a reaction in the molar quantities expressed in a chemical equation under standard conditions, all reactants and products in their standard states.
128 of 144
Enthalpy change of combustion
The enthalpy change that takes place when one mole of a substance reacts completely with oxygen under standard conditions, all products and reactants in their standard states
129 of 144
Enthalpy change of formation(of a compound)
The enthalpy change when one mole of that compound is formed from its constituent elements in their standard states under standard conditions
130 of 144
Specific heat capacity
Energy required to raise the temperature of 1g of a substance by 1 degree C
131 of 144
Bond Enthalpy
The enthalpy change that takes lace when breaking by homolytic fission 1 mole of a given bond in the molecules of a gaseous species
132 of 144
Average bond enthalpy
Average enthalpy change that takes place when breaking by homolytic fission 1 mole of a given bond in the molecules of a gaseous species
133 of 144
Hess' law
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
134 of 144
Rate of reaction
The change in concentration of reactant or product in a given time
135 of 144
Heterogeneous catalysis
Catalysis of a reaction in which the catalyst has a different physical state from the reactants
136 of 144
Homogeneous catalysis
Catalysis in which the catalyst and the reactants have the same physical state
137 of 144
Boltzmann distribution
The distribution of energies of molecules at a particular temperature
138 of 144
le Chateliers principle
When a system in dynamic equilibrium is subject to a change, the position of the equilibrium will shift to minimise the change
139 of 144
Dynamic equilibrium
The equilibrium existing in a closed system when the rate of the forward reaction equals that of the reverse reaction
140 of 144
Greenhouse effect
The process in which the absorbtion and subsequent emission of infrared radiation by atmospheric gases warms the lower atmosphere and the planet's surface
141 of 144
Troposphere
Lowest layer of the earth's atmosphere
142 of 144
Stratosphere
Second layer of the earth's atmosphere, containing the o-zone layer
143 of 144
Adsorbtion
The process that occurs when a gas, liquid, or solute is held to the surface of a solid(possibly a liquid)
144 of 144

Other cards in this set

Card 2

Front

The number of protons in the nucleus of an atom

Back

Atomic Number

Card 3

Front

The number of particles(protons and neutrons) in the nucleus

Back

Preview of the back of card 3

Card 4

Front

a positively or negatively charged atom or (covalently bonded) group of atoms(a molecular ion)

Back

Preview of the back of card 4

Card 5

Front

The mass of an atom of an isotope compared with one-twelfth of the mass of an atom of carbon-12

Back

Preview of the back of card 5
View more cards

Comments

No comments have yet been made

Similar Chemistry resources:

See all Chemistry resources »See all all resources »