Edexcel GCSE Chemistry key terms

An equation showing either the loss or the gain of electrons by one reacting species.

A negative ion formed from a halogen atom. The ions tested here are chloride, bromide and iodide.

A Group 7 element whose atoms have seven electrons in their outer shell.

Resistance to scratching, wear or indentation.

Something with the potential to cause harm, such as a corrosive chemical, a flame, hot glassware or a sharp edge.

A symbol on a chemical label that warns that the contents may harm people or the environment.

A graph showing how the temperature of a substance changes as it is heated.

Able to withstand relatively high temperatures without losing the properties needed for its use.

A six-membered arrangement of bonded atoms forming a ring.

A family of organic compounds whose members have the same general formula, differ by $CH_2$ between neighbouring members, have similar chemical properties and show a gradual variation in physical properties.

A compound that contains water molecules within its crystal structure.

A crystal containing water as part of its crystal structure.

A crystalline compound containing water as part of its crystal structure.

A compound containing carbon and hydrogen only.

A fuel containing hydrocarbons, which are compounds made from carbon and hydrogen only.

A gas produced when lithium, sodium or potassium reacts with water.

A compound of hydrogen and a halogen, with the general formula HX, where X represents a halogen.

A positively charged ion, H⁺, supplied by an acid in solution.

The amount of hydrogen ions, $H^+$, present in a given volume of solution.

A negatively charged ion with the formula OH⁻. Hydroxide compounds are included in these solubility rules, although hydroxides are not salts.

A negatively charged ion, OH⁻, supplied by an alkali in solution.

The –OH group found in an alcohol molecule.

An ending commonly used for a compound containing two elements, such as sodium chloride or magnesium oxide.

A substance present in a material but not wanted as part of its main composition.

The disposal of waste by burning it at a high temperature.

Combustion in a limited supply of oxygen, in which a fuel is only partly oxidised.

A reaction that has not proceeded to the theoretical extent expected from the limiting reactant, so less desired product forms.