all chem

Atomic number

The number of protons in the nucleus of an atom

Mass number

the total number of protons and neutrons in the nucleus of an atom

Isotopes

Atoms with the same atomic number but different mass number

Relative atomic mass

The ratio of the average mass of an atom of an element compared with one-twelfth of the mass of an atom of carbon-12.

Relative molecular mass

The ratio of the average mass of an a molecule of an element compared with one-twelfth of the mass of an atom of carbon-12.

Relative isotopic mass

The ratio of the average mass of an isotope of compared with one-twelfth of the mass of an atom of carbon-12.

First Ionisation energy

The energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions

Second ionisation energy

The energy required to remove one electron from each atom in one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions

Avogadro's number

the number of atoms that are in exactly 12g of carbon-12

Mole

the amount of a substance that contains as many particles as there are atoms in exactly 12 g of carbon-12

molar mass

The mass of a substance containing the same number of particles as there are in exactly 12g of carbon-12

empirical formula

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

molecular formula

The number of atoms of each element in one molecule of substance.

ionic bond

An electrostatic force of attraction between oppositely charged ions

covalent bond

a shared pair of electrons between two atoms

Dative covalent bond

A shared pair of electrons between two atoms, one atom of which provides both of the electrons

Metallic bond

an electrostatic force of attraction between a cation and a sea of delocalised electrons

Electronegativity

the ability of an atom to attract an electron in a covalent bond

Polar bond

the existence of partial positive and negative charges on each end of the bond as a result of the unequal sharing of electrons

s-block element

An element with its highest energy electron in an s sub-shell

p-block element

An element with its highest energy electron in a p sub-shell

Homologous series

A series of compounds with the same functional group and similar chemical properties.

Isomers

different structures that have the same molecular formula but a different arrangement of atoms

d-block element

An element with its highest energy electron in a d sub-shell

structural isomers

Have the same molecular formula but different structural formula

Chain isomers

have the same molecular formula but a different arrangement of carbon atoms in the carbon skeleton

Positional isomers

have the same molecular formula but the functional group is in a different position

Functional group isomers

Have the same molecular formula but different functional group

Functional group

An atom or a group of atoms which confer specific physical and chemical properties to the molecule.

enthalpy change

change in heat energy under constant pressure

Standard conditions

100kPa and 298K

exothermic reaction

a reaction that gives out energy to the surroundings

endothermic reaction

A reaction that takes in energy from the surroundings

Standard enthalpy of formation

Is the enthalpy change when one mole of a compound is formed from its constituent elements under standard conditions with all reactants and products in their standard states.

Ionisation Enthalpy

The first ionisation energy is the enthalpy change when one mole of gaseous atoms loses one electron per atom to produce gaseous 1+ ions

Electron affinity (1st)

The enthalpy change when one mole of gaseous atoms gain one electron per atom to produce gaseous 1- ions.

Enthalpy of atomisation

Enthalpy change when one mole of gaseous atoms is produced from an element in its standard state

Hydration enthalpy

Enthalpy change when one mole of gaseous ions become hydrated (dissolved in water)

enthalpy of solution

Enthalpy change when one mole of an ionic solid dissolves in an amount of water large enough so that the dissolved ions are well separated and do not interact with each other

Bond dissociation enthalpy

Enthalpy change when one mole of covalent bonds is broken in the gaseous state

Lattice enthalpy of formation

Enthalpy change when one mole of a solid ionic compound is formed from its constituent ions in the gas phase

Lattice enthalpy of disociation

Enthalpy change when one mole of a solid ionic compound is broken up into its constituent ions in the gas phase

Standard enthalpy of combustion

Is the enthalpy change when one mole of a substance undergoes complete combustion in an excess of oxygen under standard conditions with all reactants and products in their standard states.

Hess's Law

The enthalpy change of a reaction is independent of the route taken and depends only on the initial reactants and resulting products.

Mean Bond enthalpy

Is the enthalpy change when one mole of gaseous covalent bond are broken averaged over that bond being broken in a series of different compounds

Activation energy

Is the minimum energy required for a collision to be successful

Rate of reaction

Is the change in change in concentration of a reactant per second

Catalyst

Is a substance which increase the rate of a reaction without itself being chemically changed at the end of the reaction

How catalyst works

A catalyst provides an alternative pathway for a reaction which has a lower activation than the uncatalysed reaction

dynamic equilibrium

A reaction in which both the forward and reverse reactions are proceeding at the same rate, so the concentrations of reactants and products remain constant

Le Chatelier's Principle

If a change in conditions is imposed on a system at equilibrium, the position of equilibrium will shift to oppose the change

Oxidation

Is the loss of electrons, gain of oxygen, loss of hydrogen or increase in oxidation number

Reduction

Is the gain of electrons, loss of oxygen, gain of hydrogen or decrease in oxidation number

Oxidising agent

Is an electron acceptor

Reducing agent

Is an electron donor

Oxidation number

Is the charge that would be on an atom if the bonding were completely ionic

redox reaction

a reaction in which electrons are transferred from one species to another, meaning both oxidation and reduction occurs

Stereoisomers

Have the same molecular and structural formula but a different arrangement of atoms in a 3D space

Geometrical isomers

have the same molecular formula but a different spatial arrangement of atoms around a double bond

Electrophile

An electron pair acceptor

Nucleophile

An electron pair donor

Free Radical

A species with an unpaired electron

Homolytic fission

Breaking of a covalent bond in such a way that one electron goes to each atom to form free radicals

Heterolytic fission

Breaking of a covalent bond in such a way that both electrons go to the same atom

Hydration

Use of water to break covalent bonds

Unsaturated

an organic compound that contains at least one carbon-carbon double or triple bond

Saturated

an organic compound that does not contain a carbon-carbon double or triple bond but instead just has single bonds

addition polymerisation

Combination of a large number of monomers to form a single chain

Biofuel

fuel derived from renewable biological sources

Formation formula

Products- reactants

Combustion formula

Reactants -products

Mean bond enthalpy formula

Bonds broken- bonds formed

spontaneous reaction

A reaction that occurs without a constant input of energy

Entropy

a measure of the disorder of a system

Addition reaction

Two species join together to make one molecule, usually accompanied by breaking of double bond

Substitution reaction

one functional group on a molecule is swapped for a different one

Elimination reaction

One molecule breaks up to form two molecules, usually forms a double bond

Carbocation

An ion that contains a positively charged carbon atom

Carboanion

an ion that contains a negatively charged carbon atom

Fractional distillation is used to

Separate a mixture of different liquids and uses the fact that different liquids have different boiling points

C1-C4 20°c

Liquified petroleum gas

C5-C9 70°c

Naptha

C5-C10 120°c

Petrol

C10-C16 170°c

Kerosine

C14-C20 270°c

Diesel fuels

C20-C50

Lubricating oils

C30-C70 600°c

Fuel oil

C70

Residue (bitumen)

Cracking

is the breaking down of larger, less useful hydrocarbons into shorter, more useful ones heated in the absence of air

Catalytic Cracking uses a \____ catalyst

Zeolite

Catalytic cracking temperature

450°c

Catalytic cracking proceeds by a \________ mechanism

Carbocation

Catalytic cracking produces more

Highly branched alkane isomers, cyclic and aromatic compounds

Fuel

Is a store of energy that can be released on demand

Thermal cracking temp

400-900°c

Thermal cracking pressure

7000kPa

Catalytic converters produce less

Co, hydrocarbons, nitrogen oxides, hydrogen, oxygen

Catalytic converters produce more

CO2, N2

Catalytic converted is a honeycomb structure coated in

Platinum

Greenhouse gases absorb some of \___ emitted by earth and reflect some back towards earth

IR radiation