Chemistry Module two key words

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  • Created by: ciara4466
  • Created on: 25-02-18 20:53
Empirical formula
A formula which shows the simplest whole number ratio of atoms of each element in a compound.
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Molecular formula
A formula which shows the actual number of atoms of each element in a molecule.
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Molar gas volume
The volume of one mole of gas under specified conditions of temperature and pressure e.g. 24dm at 20°C and one atmosphere pressure.
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Homologus series
Compounds which have the same general formula, similar chemical properties and successive members differ by CH2.
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Functional group
The part of a structure which determines the characteristic reactions of the compound.
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Structural isomers
Molecules which have the same molecular formula but a different structural formula.
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Stereoisomers
Have the same structural formula but different 3D spatial arrangements (are non-superimposable)
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Saturated hydrocarbons
Contains no C=C or C≡C bond.
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Hydrocarbon
Contains hydrogen and carbon only.
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Thermal cracking
Breaking down large molecules into smaller molecules using heat.
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Substitution
Replacing one atom or group with a different atom or group.
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Homolytic fission
Bond breaking in which one of the shared electrons goes to each atom.
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Free radical
A particle with an unpaired electron.
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Catalyst
A substance which alters the speed of a chemical reaction but does not get used up.
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Unsaturated Hydrocarbon
Contains at least one C=C or C≡C bond.
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Sigma bond
A covalent bond formed by the linear overlap of atomic orbitals resulting in free rotation along the bond axis.
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Pi bond
A covalent bond formed by the sideways overlap of p orbitals resulting in it being restricted along the bond axis.
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Bond length
The distance between the nuclei of two covalently bonded atoms.
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Hydrogenation
Addition of a hydrogen molecule across a C=C.
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Electrophile
An ion or molecule that attacks regions of high electron density.
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Heterolytic fission
Bond breaking in which the shared electrons go to one atom.
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Polymerisation
Joining together of small molecules (monomers) to form a large molecule – see also 5.16.1
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Primary alcohol
An alcohol which has only one carbon directly attached to the same carbon as the –OH group. (exception is methanol)
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Secondary alcohol
An alcohol which has two carbons directly attached to the same carbon as the –OH group.
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Tertiary Alcohol
An alcohol which has three carbons directly attached to the same carbon as the –OH group.
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Reflux
Repeated boiling and condensing of a reaction mixture.
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Nucleophile
An ion or molecule, with a lone pair of electrons, that attacks regions of low electron density.
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Hydrolysis
Breaking up of molecules by reaction with water.
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Elimination
A reaction in which a small molecule is removed from a larger molecule.
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Miscibility
Liquids which mix in all proportions i.e. form a single layer.
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Esterification
A reaction between an alcohol and a carboxylic acid or acyl chloride to produce an ester.
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Endothermic
A reaction in which the enthalpy of the products is greater than the enthalpy of the reactants.
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Exothermic
A reaction in which the enthalpy of the products is less than the enthalpy of the reactants.
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Standard conditions
25°C (298k) and 1 atmosphere (100kPa).
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Enthalpy of reaction
Enthalpy change when the number of moles of substances, are as written in the equation.
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Standard enthalpy of combustion
The enthalpy change when one mole of a substance is completely burnt in oxygen under standard conditions
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Standard enthalpy of formation
The enthalpy change when one mole of a compound is formed from its elements under standard conditions.
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Standard enthalpy of neutralisation
The enthalpy change when one mole of water is produced in a neutralisation reaction under standard conditions.
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Conservation of energy
Energy cannot be created or destroyed but it can change from one form to another.
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Hess' law
The enthalpy change for a reaction is independent of the route taken, provided the initial and final conditions are the same.
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Average bond enthalpy
The energy required to break one mole of a given bond averaged over many compounds
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Reversible
A reaction which goes in both the forward and backward directions.
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Dynamic (equilibria)
Rate of forward reaction is equal to the rate of the backward reaction.
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Equilibrium
A reversible reaction in which the amount of each reactant / product remains constant.
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Homogeneous
A reaction in which all the reactants and products are in the same physical state.
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Reaction rate
A reaction in which all the reactants and products are in the same physical state.
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Reaction rate
The change of the concentration (amount) of a reactant or product with respect to time.
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Activation energy
The minimum amount of energy required for a reaction to occur.
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s-block element
An element which has an atom with highest energy/outer electron in an s-subshell (orbital).
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Basic
Proton acceptor.
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Other cards in this set

Card 2

Front

A formula which shows the actual number of atoms of each element in a molecule.

Back

Molecular formula

Card 3

Front

The volume of one mole of gas under specified conditions of temperature and pressure e.g. 24dm at 20°C and one atmosphere pressure.

Back

Preview of the back of card 3

Card 4

Front

Compounds which have the same general formula, similar chemical properties and successive members differ by CH2.

Back

Preview of the back of card 4

Card 5

Front

The part of a structure which determines the characteristic reactions of the compound.

Back

Preview of the back of card 5
View more cards

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