Key terms & definitions

The arrangement of electrons found in a Group 0 atom, with a complete outer electron shell.

The ‘Sad Night’: the Spanish retreat from Tenochtitlan on the night of 30 June 1520, during which many Spaniards and their allies were killed.

A pattern with no clear tendency for y to increase or decrease as x increases.

A classification used when there is no clear overall trend. AQA uses this description for coefficients strictly between $-0.2$ and $0.2$.

Being active mainly at night.

A point on a stationary wave that does not vibrate.

A fixed point on a stationary wave where there is no vibration.

A point in a tree. In a Huffman tree, a node represents either a character and its frequency or a group of characters and their combined frequency.

Unwanted or excessive sound that disturbs people or their surroundings.

A way of life involving movement from place to place rather than permanent settlement; many Plains bands moved seasonally to follow buffalo herds.

A way of life involving movement from place to place rather than permanent settlement, often following seasonal food supplies.

The exposed ground between opposing armies’ front-line trenches.

A heat-resistant synthetic fibre used in protective textiles for situations with a high risk of fire exposure.

The intended or target size stated for a component.

The intended or target measurement stated on a drawing or specification.

The stated or target value of a component, such as the resistance printed on a resistor.

The unelected assembly selected by the army and its supporters to govern in 1653. It was also known as Barebone’s Parliament or the Parliament of Saints.

An agreement in which countries promise not to attack one another.

A build-up of fat in the liver that is not caused by excessive alcohol consumption; it is often associated with being overweight.

A build-up of fat in the liver, often linked to being overweight. It is also known as metabolic dysfunction-associated steatotic liver disease (MASLD).

A solvent other than water, such as ethanol or propanone.

A solvent other than water, such as hexane.

Not readily broken down by microorganisms, so it can persist in the environment for a long time.

Not readily broken down by microorganisms, so it can persist in the environment.

A calculation completed using written or mental methods rather than a calculator.

DNA that does not code for a protein; some of it controls whether genes are switched on or off.

A person who does not take part in fighting, such as a child or a civilian caught up in a war.

A person who is not taking part in the fighting, such as a civilian.

Military service that does not involve fighting, such as medical or other support duties.

A disease that cannot be passed from one organism to another; many such diseases are long-lasting and may worsen over time.