Chemistry Paper 2 Definitions

Front 1

activation energy

Back 1

the minimum energy required to start a reation by the breaking of bonds

Front 2

atom economy

Back 2

molecular mass of the desired product/sum of molecular masses of all products

Front 3

Boltzmann distribution

Back 3

the distribution of energies of molecules at a particular temperature

Front 4

bond enthalpy

Back 4

the enthalpy change that takes place when breaking by homolytic fission 1 mol of a given bond in the molecules of a gaseous species

Front 5

cis-trans isomerism

Back 5

a special type of E/Z isomerism in wich there is a non-hydrogen group and hydrogen group on each C of a C=C bond. the cis isomer has the hydrogen on the same side and the trans has the hydrogen on opposite sides of the C=C bond

Front 6

curly arrow

Back 6

a symbol used in reaction mechanisms to show the movement of an electron pair in the breaking or formation of a covalent bond

Front 7

displayed formula

Back 7

a formula showing the relative positioning of all the atoms in a molecule and the bonds between them

Front 8

E/Z isomerism

Back 8

a type of stereoisomerism in which different groups attached to each carbon of a C=C bond may be arranged differently in space because of the restricted rotation of the C=C bond

Front 9

electrophile

Back 9

an atom that is attracted to an electron rich centre or atom, where it accepts a pair of electrons to form a new covalent bond

Front 10

standard enthalpy change of combustion

Back 10

the enthalpy change that takes place when one mole of a substance reacts completely with oxygen under standard conditions, all products and reactants being in their standard states

Front 11

standard enthalpy change of formation

Back 11

the enthalpy change that takes place when one mole of a compound in its standard state is formed from its constituent elements in their standard states under standard conditions

Front 12

standard enthalpy change of reaction

Back 12

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 standard states

Front 13

functional group

Back 13

the part of an organic molecule responsible for its chemical reactions

Front 14

general formula

Back 14

the simplest algebraic formula of a member of a homologous series

Front 15

greenhouse effect

Back 15

the process in which the absorption an subsequent emission of infrared radiation by atmospheric gases warms the lower atmosphere and the planet's surface

Front 16

heterolytic fission

Back 16

the breaking of a covalent bond with both of the bonded electrons going to one of the atoms forming a cation and an anion

Front 17

homologous series

Back 17

a series of organic compounds with the same functional group but with each successive member differing by CH2

Front 18

homolytic fission

Back 18

the breaking of a covalent bond with one of the bonded electrons going to each atom forming two radicals

Front 19

hydrocarbon

Back 19

an organic compound of only hydrogen and carbon

Front 20

le chateliers principle

Back 20

when a system in dynamic equilibrium is subjected to a change, the position of equilibrium will shift to minimise the change

Front 21

nucleophile

Back 21

an atom or group of atom that is attracted to an electron deficient centre or atom where it donates a pair of electrons to form a new covalent bond

Front 22

radical

Back 22

a species with a unpaired electron

Front 23

skeletal formula

Back 23

a simplified organic formula with hydrogen atoms removed from alkyl chains leaving just a carbon skeleton and associated functional groups

Front 24

stereoisomers

Back 24

compounds with the same structural formula but a different arrangement of the atoms in space

Front 25

structural formula

Back 25

a formula showing the minimal detail for the arrangement of atoms in a molecules

Front 26

structural isomers

Back 26

molecules with the same molecular formula but with different structural formula

Front 27

standard conditions

Back 27

a pressure of 100KPa, 25 degrees Celsius and concentration of 1 mol/dm

Front 28

molecular formua

Back 28

the number of atoms in each element in a molecule

Front 29

empirical formua

Back 29

the simplest whole number ratio of atoms of each element present in a compound