Definitions

Hydrocarbon

A compound containing only carbon and hydrogen atoms.

Functional Group

A group of atoms in an organic molecule responsible for the chemical characteristics of a compound.

Homologous Series

A series of compounds with the same general formula, similar chemical properties and containing the same functional group.

Saturated Hydrocarbon

A hydrocarbon containing only single bonds.

Curly Arrows

A symbol used in mechanisms to show the movement of electron pairs.

Exothermic Reaction

Reaction where the enthalpy of the products is less than the enthalpy of the reactants, resulting in heat being released into the surroundings. Exothermic is bond making.

Endothermic Reaction

Reaction where the enthalpy of the products is greater than the enthalpy of the reactants, resulting in heat being taken in from the surroundings. Endothermic is bond breaking.

Incomplete Combustion

Combustion that occurs in a limited supply of oxygen, forming carbon monoxide.

Radical

A species with an unpaired electron.

Nucleophile

Contains a lone pair of electrons which can be donated.

Electrophile

An atom or group of atoms that are attracted to an electron-rich region, where it accepts a pair of electrons.

Homolytic Fission

Breaking of a covalent bond to form two radicals, each with an unpaired electron.

Heterolytic Fission

Breaking of a covalent bond to form two oppositely charged ions.

Structural Isomer

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

Stereoisomer

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

E/Z Stereoisomer

A type of stereoisomer where different groups attached to each carbon in a $C=C$ bond are arranged differently in space, due to the restricted rotation of the double bond.

Atom Economy

This is a measure of the amount of waste produced during a reaction. It is defined as:
$$ \text{atom economy} = \frac {\text{Mr of desired product}}{\text{Sum of Mr of all products}} \times 100 $$

Percentage Yield

This is a measure of how much of the reactants is turned into products. It is defined as:
$$ \text{yield} = \frac {\text{actual product, mol}}{\text{theoretical product, mol}} \times 100 $$

Standard Enthalpy change of formation

This is the enthalpy change when one mole of a compound is formed from its constituent elements, in their standard states, under standard conditions.

Standard enthalpy change of combustion

The enthalpy change when a reaction occurs in the molar quantities stated in the balanced equation, in their standard states, under standard conditions.

Standard Conditions

A temperature of 298K, an atmosphere of 100kPa and a concentration of $1 mol\,dm^{-3}$ for solutions.

Average Bond Enthalpy

The average change in enthalpy that occurs when the covalent bonds in one mole of gaseous are broken.

Activation Energy

The minimum energy required in order to start a reaction.

Catalyst

Provides an alternative reaction route in order to lower the activation energy without being consumed itself.

Le Chatelier's Principle

This states that when a system in equilibrium is subjected to change, the position of equilibrium will shift in order to minimise the effect of the change.

© Andrew Deniszczyc, 2018