Hard defn Flashcards
First ionisation energy
The minimum amount of energy required to remove the first the most loosely bound electron from a mole of isolated atoms of an element in its neutral gaseous ground state.
Limiting reactant
The reactant that is fully consumed when a reaction goes to completion.
Theoretical yield
The quantity of product that should form when all of the limiting reactant reacts. To get the theoretical yield use the molar ratio from the balanced equation between the limiting reactant and product.
Salts
A salt is formed when the H+ of an atom is replaced of a metal or ammonium ion.
Ionic bond
Formed due to the electrostatic attraction between oppositely charged ions cause by the complete transfer of electrons form one to another.
Pure covalent bonding
Occurs when electrons are shared equally.
Polar covalent bonding
Occurs when electrons are shared unequally.
Dative covalent bonding
Only one atom supplies the electrons needed to make a covalent bond. In a dative covalent bond one atom supplies both the electrons being shared in the bond.
Polar molecule
The slight positive and slight negative poles of a molecule are separated by a distance, they do not coincide.
Hydrogen bonding
An intermolecular force of attraction that occurs when hydrogen is bonded to a small more electronegative element such as N, O or F.
Standardise
To find out the concentration of a solution by colorimetry or titration.
Bonding pairs of electrons
Pairs of electrons in the outer shell that are shared between atoms.
Lone pairs of electrons
Pairs of electrons in the outer shell of the atom that do not take part in bonding.
Valence shell electron pair repulsion theory.
Pairs of electrons in the outer shell arrange themselves to be as far away from each other as possible so as to minimise the repulsions between them.
Heat of reaction
The heat change that occurs when a reaction takes place according to a balanced chemical equation.
Exothermic reaction
A reaction where heat is lost from the reaction to the surroundings.
Endothermic reaction
A reaction where heat is taken in by the reaction from the surroundings.
Heat of combustion
The heat change that occurs when 1 mole of a substance is burned in an excess of oxygen.
Kilogram calorific value
The heat that is produced when 1 kilogram of a substance is burned in an excess of oxygen.
Heat of formation
The heat change that occurs when 1 mole of a substance is formed from its elements in their standard states.
Hess’ law
When a reaction takes place in stages the sum of the heat changes of the individual stages equals the heat change if the reaction were to take place in one stage.
Hydrocarbon
A compound that consist of the elements carbon and hydrogen only.
Saturated
Contains a single bonds between carbon atoms.
Unsaturated
Contains a multiple bond between two carbon atoms.