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.
Aromatic
Contains a benzene ring in the structure.
Aliphatic
Straight or branched chained molecule.
Ionic addition reaction
Two reactants to form one main product.
Free radical substitution reaction
An atom or group of atoms is replaced by an atom or group of atoms.
Condensation reaction
Two different molecules combine to form a more complex molecule with the production of a smaller molecule such as water.
Esterification reaction
An alcohol and a carboxylic acid react reversibly to form an ester and water. This is an example of a condensation reaction.
Elimination reaction
A smaller molecule is removed from a larger molecule. A double bond is found in one of the product molecules.
Dehydration reaction
Removal of water from a molecule. This is an elimination reaction.
Hydrogenation reaction
Addition of hydrogen to an alkene molecule involving a nickel catalyst and 200C.
Hetrolytic fission
A molecule splits to form two different ions.
Homolytic fission
A molecule splits to form two identical atoms using u.v light.
Polymerisation reaction
A reaction where many small molecules called monomers combine together to form a very large molecule called a polymer.
Boyles law
At a constant temperature, the volume of a fixed mass of any gas is inversely proportional to the pressure of the gas.
Charles law
At a constant pressure, the volume of a fixed mass of any gas is directly proportional to the absolute temperature.
Avogadro’s law
Equal volumes of all gases under the same conditions of temperature and pressure contain equal numbers of molecules.
Gay-lussac’s law of combining volumes
When gases react, the volumes consumed in the reaction bear a simple whole number ratio to each other and to the volumes of any gaseous product of the reaction, all volumes measured under the same conditions of temperature and pressure.
Electrolyte
A substance that in the molten or dissolved state can conduct electricity.
Electrochemical series
A list of elements arranged in order of their tendency to lose electrons.
Displacement reaction
A reaction where a metal will take the place of a less reactive metal from a solution of its salts.
Electrolysis
A process that uses electricity to bring about a chemical reaction.
Rate of reaction
The change in concentration per unit time of any one reactant or product.
Catalyst
A substance that alters the rate of a reaction without itself being used up in the reaction.
Heterogenous catalysis
The catalyst and the reactants are in different phases.
Homogenous catalysis
The catalyst and the reactants are in the same phase.
Autocatalysis
The catalyst is a product of the reaction.
Activation energy
The minimum amount of energy colliding molecules must have in order for a reaction to take place.
Indicator
A substance that changes colour depending on the pH of the solution in which it is placed.
Hard water
Water that does not form a lather easily.
Temporary hardness
Can be removed by boiling. Caused by calcium and magnesium hydrogencarbonates.
Permanent hardness
Cannot be removed by boiling. Caused by calcium and magnesium sulfates.
Biochemical oxygen demand
The amount of dissolved oxygen consumed by biochemical action when a sample of water was kept in the dark for 5 days.
Fractional distillation
Separation of components of crude oil based on them having different boiling points.
Steam distillation
Two immiscible liquids together have a lower boiling point than either of the liquids on their own.
Chromatography
A mobile phase carries a mixture through a stationary phase. Separation happens because some of the components of the mixture are attracted to significantly different extents to the mobile or stationary phase.
Recrystallisation
More solute in a hot solvent than in a cold one.
Colorimetry
Concentration of solute is proportional to colour intensity of solution.
