Physical keywords

Isotope

Different number of neutrons, same number of protons

Relative atomic mass

Average mass of an atom of an element compared to the mass of 1/12th of carbon 12

Ionisation energy

The amount of energy required to remove 1 mole of an electron from 1 mole of gaseous atom to become 1 mole of gaseous ion

Dative covalent

One atom donates shared pair of electrons

Electronegativity

Ability of an atom to attract pair of electrons towards itself in a covalent bond

Enthalpy change

Heat energy change measured under conditions of constant pressure

The standard enthalpy change of formation

Enthalpy change when 1 mole of the compound is formed from its elements under standard conditions, all reactants and products being in their standard states.

The standard enthalpy of combustion of a substance

Enthalpy change that occurs when one mole of a substance is combusted completely in oxygen under standard conditions, all reactants and products being in their standard states

Mean bond enthalpy

Energy required to break covalent bond into gaseous atoms, averaged over different molecules