Key terms & definitions

The condition in which the concentrations of hydrogen ions and hydroxide ions are equal; a neutral solution has pH 7.

The condition in which a solution has equal concentrations of hydrogen ions and hydroxide ions. At room temperature, its pH is approximately 7.

An object with equal total positive and negative charge, so it has no overall charge.

A solution with pH 7, so it is neither acidic nor alkaline.

A solution with equal concentrations of hydrogen ions, $H^+$, and hydroxide ions, $OH^-$. On the usual GCSE pH scale, a neutral solution has pH 7.

The blue conductor that completes the normal circuit and is at or close to earth potential, approximately 0 V.

The blue-insulated wire that completes the mains circuit and is at, or close to, earth potential (0 V).

A particle with no electrical charge found in an atom's nucleus.

An uncharged particle found in atomic nuclei and sometimes emitted during nuclear processes.

A subatomic particle found in the nucleus with no electrical charge: its relative charge is 0.

Radiation consisting of neutrons emitted from unstable nuclei.

An extremely dense remnant that can be left after a supernova.

The Prophets: the section of the Tenakh containing accounts of Israelite history and prophetic teachings.

A recent or developing innovation that changes how products are designed, manufactured or distributed.

The city established by Hasdrubal the Fair as Qart Hadasht in Iberia, later called Carthago Nova by the Romans; modern Cartagena.

The peace terms presented by Parliament to Charles I in July 1646, demanding major changes to religion and restrictions on royal power.

The programmes and reforms introduced by President Franklin D. Roosevelt from 1933 to tackle the Great Depression.

Lenin's economic policy introduced in 1921, allowing private farming, trade and small businesses while retaining state control of major economic sectors.

France’s colonial possessions in North America, including Canada.

President John F. Kennedy's programme to improve American society through economic growth, greater opportunity and reforms addressing problems including poverty, education and health.

An approach to increasing food production that aims to benefit poorer farmers while conserving the environment.

A period from the late 1960s into the early 1980s when Hollywood gave greater opportunities to director-led filmmaking, stylistic experimentation and challenging subject matter.

The intensified expansion of overseas empires in the late nineteenth and early twentieth centuries, driven by rivalry, resources, markets and claims of a civilising mission.

Spanish legislation introduced in 1542 to protect Indigenous people from enslavement and exploitation and restrict the encomienda system.

The belief that government action against poverty, sickness and unemployment could increase people’s real freedom and opportunities.

Supporters of the emotional, evangelical religious revivals associated with the Great Awakening.

A country experiencing rapid economic growth and an increasing importance of manufacturing and services, although poverty and inequality may remain.

A country experiencing industrial growth and an increasing role for manufacturing and services in its economy.

A country undergoing substantial industrial growth and economic change, although incomes and living standards remain uneven.

A man who rejects traditional masculine expectations and actively shares domestic work and childcare.