chemistry

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activation energy
The minimum energy required to start a reaction by the breaking of bonds
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addition reaction
A reaction in which a reactant is added to an unsaturated molecule to make a saturated molecule.
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atomic orbital
A region within an atom that can hold up to two electrons, with opposite spins
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average bond enthalpy
The 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.
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Avogadro constant
The number of atoms per mole of the carbon-12 isotope (6.02 × 1023 mol–1 .)
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base
A species that is a proton acceptor. biodegradable material A substance that is broken down naturally in the environment by living organisms.
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bond enthalpy
The enthalpy change that takes place when breaking by homolytic fission 1 mol of a given bond in the molecules of a gaseous species.
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carbanion
An organic ion in which a carbon atom has a negative charge.
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carbocation
An organic ion in which a carbon atom has a positive charge.
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catalyst
A substance that increases the rate of a chemical reaction without being used up in the process.
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coordinate bond
A shared pair of electrons which has been provided by one of the bonding atoms only; also called a dative covalent bond.
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covalent bond
A bond formed by a shared pair of electrons.
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cracking
The breaking down of long-chained saturated hydrocarbons to form a mixture of shorter-chained alkanes and alkenes.
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dative covalent
A shared pair of electrons which has been provided by one of the bonding atoms only; also called a coordinate bond.
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delocalised electrons
Electrons that are shared between more than two atoms.
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E/Z isomerism
A type of stereoisomerism 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 bond.
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electron configuration
The arrangement of electrons in an atom.
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electronegativity
A measure of the attraction of a bonded atom for the pair of electrons in a covalent bond.
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electron shielding
The repulsion between electrons in different inner shells. Shielding reduces the net attractive force from the positive nucleus on the outer-shell electrons.
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electrophile
An atom (or group of atoms that is attracted to an electron-rich centre or atom, where it accepts a pair of electrons to form a new covalent bond.
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electrophilic addition
A type of addition reaction in which an electrophile is attracted to an electron-rich centre or atom, where it accepts a pair of electrons to form a new covalent bond.
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elimination reaction
The removal of a molecule from a saturated molecule to make an unsaturated molecule.
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empirical formula
The simplest whole-number ratio of atoms of each element present in a compound.
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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 (∆H +ve) .
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enthalpy
The heat content that is stored in a chemical system.
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(standard) enthalpy change of combustion
∆Hc ө The enthalpy change that takes place when one mole of a substance reacts completely with oxygen under standard conditions, all reactants and products being in their stand
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(standard) enthalpy change of formation
∆Hf ө 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.
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(standard ) enthalpy change of reaction
∆Hr ө 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
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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 (∆H –ve) .
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fractional distillation
The separation of the components in a liquid mixture into fractions which differ in boiling point and hence chemical composition by means of distillation, typically using a fractionating column
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giant covalent lattice
A three-dimensional structure of atoms, bonded together by strong covalent bonds. giant ionic lattice A three-dimensional structure of oppositely charged ions, bonded together by strong ionic bonds.
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giant metallic lattice
A three-dimensional structure of positive ions and delocalised electrons, bonded together by strong metallic bonds.
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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.
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hydrocarbon
A compound of hydrogen and carbon only.
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hydrogen bond
A strong dipole–dipole attraction between an electron-deficient hydrogen atom (O–Hδ+ or -–Hδ+ ) on one molecule and a lone pair of electrons on a highly
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hydrolysis
A reaction with water or aqueous hydroxide ions that breaks a chemical compound into two compounds.
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initiation
The first step in a radical substitution in which the free radicals are generated by ultraviolet radiation.
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intermolecular force
An attractive force between neighbouring molecules. Intermolecular forces can be van der Waals’ forces (induced dipole–dipole forces , permanent dipole–dipole forces or hydrogen bonds.
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ion
A positively or negatively charge atom or (covalently) bonded group of atoms (a molecular ion) .
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ionic bonding
The electrostatic attraction between oppositely charged ions.
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(first) ionisation energy
The energy required to remove one electron from each atom in one mole of gaseous atoms of that element
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(second) ionisation energy
The energy required to remove one electron from each ion in one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions.
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(successive) ionisation
A measure of the energy required to remove each electron in turn, C2 | Chemistry 7/10 energy e.g. the second ionisation energy is the energy required to remove one electron from each ion in one
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isotopes
Atoms of the same element with different numbers of neutrons and different masses.
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lone pair
An outer-shell pair of electrons that is not involved in chemical bonding.
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mass (nucleon) number
The number of particles (protons and neutrons in the nucleus.)
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mechanism
A sequence of steps showing the path taken by electrons in a reaction.
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metallic bond
The electrostatic attraction between positive metal ions and delocalised electrons.
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molar mass, M.
The mass mole of a substance. The units of molar mass are g mol–1.
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molar volume
The volume per mole of a gas. The units of molar volume are dm3 mol–1. At room temperature and pressure the molar volume is approximately 24.0 dm3 mol–1.
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mole
The amount of any substance containing as many particles as there are carbon atoms in exactly 12 g of the carbon-12 isotope.
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molecular formula
The number of atoms of each element in a molecule.
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oxidation
Loss of electrons or an increase in oxidation number
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periodicity
A regular periodic variation of properties of elements with atomic number and position in the Periodic Table.
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permanent dipole
A small charge difference across a bond resulting from a difference in electronegativities of the bonded atoms.
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permanent dipole– dipole force
An attractive force between permanent dipoles in neighbouring polar molecules.
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pi -bond (π -bond)
The reactive part of a double bond formed above and below the plane of the bonded atoms by sideways overlap of p-orbitals.
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polar covalent bond
A bond with a permanent dipole.
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polar molecule
A molecule with an overall dipole, taking into account any dipoles across bonds.
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propagation
The two repeated steps in radical substitution that build up the products in a chain reaction.
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relative atomic mass, Ar
The weighted mean mass of an atom of an element compared with one-twelfth of the mass of an atom of carbon-12.
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relative formula mass
The weighted mean mass of a formula unit compared with one- twelfth of the mass of an atom of carbon-12.
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relative isotopic mass
The mass of an atom of an isotope compared with one-twelfth of the mass of an atom of carbon-12.
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relative molecular mass, Mr
The weighted mean mass of a molecule compared with one- twelfth of the mass of an atom of carbon-12.
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shell
A group of atomic orbitals with the same principal quantum number, n. Also known as a main energy level.
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simple molecular lattice
A three-dimensional structure of molecules, bonded together by weak intermolecular forces.
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species
Any type of particle that takes part in a chemical reaction. specific heat capacity, c The energy required to raise the temperature of 1 g of a substance by 1 °C.
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spectator ions
Ions that are present but take no part in a chemical reaction.
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standard conditions
A pressure of 100 kPa (1 atmosphere) , a stated temperature, usually 298 K (25 °C ), and a concentration of 1 mol dm–3 (for reactions with aqueous solutions .)
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standard solution
A solution of known concentration. Standard solutions are normally used in titrations to determine unknown information about another substance.
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standard state
The physical state of a substance under the standard conditions of 100 kPa (1 atmosphere) and 298 K (25 °C .)
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stereoisomers
Compounds with the same structural formula but with a different arrangement of the atoms in space.
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stoichiometry
The molar relationship between the relative quantities of substances taking part in a reaction. stratosphere The second layer of the Earth’s atmosphere, containing the ‘ozone layer’, about 10 km to 50 km
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structural formula
A formula showing the minimal detail for the arrangement of atoms in a molecule.
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structural isomers
Molecules with the same molecular formula but with different structural arrangements of atoms.
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sub -shell
A group of the same type of atomic orbitals (s, p, d or f) within a shell.
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substitution reaction
A reaction in which an atom or group of atoms is replaced with a different atom or group of atoms.
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termination
The step at the end of a radical substitution when two radicals combine to form a molecule.
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unsaturated hydrocarbon
A hydrocarbon containing carbon-to-carbon multiple bonds.
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van der Waals’ forces
Very weak attractive forces between induced dipoles in neighbouring molecules
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Other cards in this set

Card 2

Front

A reaction in which a reactant is added to an unsaturated molecule to make a saturated molecule.

Back

addition reaction

Card 3

Front

A region within an atom that can hold up to two electrons, with opposite spins

Back

Preview of the back of card 3

Card 4

Front

The 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.

Back

Preview of the back of card 4

Card 5

Front

The number of atoms per mole of the carbon-12 isotope (6.02 × 1023 mol–1 .)

Back

Preview of the back of card 5
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