Ocr As Chemistry Key Words

The number of protons in the nucleus of an atom.

The number of protons and neutrons in the nucleus of an atom.

The mass of an atom of an isotope compared with 1/12 of the mass of an atom ofC-12.

The weighted mean mass of an atom of an element compared with 1/12 of the mass of an atom of C-12.

Atoms of the same element with a different number of neutrons.

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

Highest energy sub-shell is a s/p/d sub-shell.

Release H+ ions in solution (proton donor).

A proton acceptor.

A soluble base that release OH- ions when in solution.

A compound produced when a H+ ion from an acid is replaced by a metalor another positive ion, such as the ammonium ion.

The amount of substance containing as many particles as there are carbon atoms inexactly 12g of C-12.

The number of particles per mole of a substance (6.02x1023).

The mass, in g, per mole of a substance. Units are gmol-1.

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

The actual number of atoms of each element in a molecule.

The water present in a compound giving the compound a crystalline appearance.

When all the waters of crystallisation havebeen removed from a compound.

When water of crystallisation is present in a crystal compound.

The energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions. Units are kJ mol-1.

A measure of the energy required to remove each electron in turn.

The electrostatic attraction between oppositely charged ions.

The sharing of a pair of electrons between two atoms.

The sharing of a pair of electrons between two atoms where only one of the atomssupplies both the electrons shared.

The ability of an atom to attract the bonding electrons towards itself in acovalent bond.

The attraction of positive metal ions to delocalised electrons.

The repeating pattern of trends across different periods.

A measure of the number of electrons that an atom uses to bond with atoms of adifferent element.

The loss of electrons / an increase in oxidation number (state).

A reagent which oxidises another species (gets reduced itself).

The gain of electrons / a decrease in oxidation number (state).

A reagent which reduces another species (gets oxidised itself).

A reaction where both oxidation and reduction take place.

A reaction in which a more reactive element displaces a less reactive element from an aqueous solution of its halide ions.

A reaction in which an element is simultaneously oxidised and reduced.

A dipole-dipole attraction between a slightly positive hydrogen on one molecule and a lone pair of electrons on a highly electronegative atom (N, O, F) of another molecule.

A compound containing only hydrogen and carbon only.

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

A group of atoms responsible for the characteristic reactions of a compound.

Containing single bonds only.

Containing at least one carbon - carbon double bond.

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

The actual number of atoms of each element in a molecule.

Compounds with the same molecular formula but a different structural formula.

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

An example of stereoisomerism, in terms of restricted rotation about a double bond and the requirement for two groups to be attached to each carbon of the carbon - carbon double group.

A special case of E/Z isomerism in which two of the substituent groups are the same.

Separation of a liquid mixture into fractions with different boiling points.

The breaking down of long chained saturated hydrocarbons to form more useful and shorter chained alkanes and alkenes.

A fuel that is derived from recently living material such as plants or from the waste of animals.

The movement of an electron pair, showing either the breaking or formation of a covalent bond

A species with an unpaired electron.

The breaking of a covalent bond where the shared pair of electrons are split equally forming two radicals.

The breaking of a covalent bond where the shared pair of electrons are not equally split, forming a cation and an anion.

Species attracted to an electron rich centre where it accepts a pair of electrons to form a new covalent bond.

A species that is attracted to an electron deficient centre where it donates a pair of electrons to form a new covalent bond.

Heat is given out to the surroundings (reactants lose energy).

Heat is taken from the surroundings (reactants gain energy).

The minimum energy required to start a reaction by the breaking of bonds.

A pressure of 1 atmosphere, 25 degrees celcius, and a concentration of 1.00 moldm - 3.

The enthalpy change that accompanies a reaction in the molar quantities expressed in a chemical equation (under standard conditions).

The enthalpy change that takes place when one mole of a compound is formed from its constituent elements (in standard conditions).

The enthalpy change that takes place when one mole of a substance reacts completely with oxygen (in standard conditions).

The average enthalpy change that takes place when breaking by homolytic fission, one mole of a given type of bond in the molecules of a gaseous species.

Speeds up a reaction without being consumed by the overall reaction.

The ease at which a liquid turns into a gas.

The equilibrium that exists in a closed system when the rate of forward reaction is equal to the rate of the reserve reaction.

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