Key terms & definitions

A formula showing the actual number of atoms of each element in one molecule.

An ion formed from a whole molecule without its breaking into smaller fragments.

The study of evolutionary relationships using biological molecules, particularly comparisons of DNA sequences.

The study of evolutionary relationships by comparing biological molecules, such as DNA.

The three-dimensional arrangement of atoms bonded together in a molecule.

A structure with spaces of a suitable size that allow some particles through while excluding others.

A group of atoms joined by covalent bonds that exists as a separate unit.

A particle made from two or more atoms chemically bonded together.

A group of atoms held together by covalent bonds.

The amount of substance containing a specified number of particles; it is not a unit of mass.

The relative amounts in moles of the substances taking part in a reaction.

The relative proportions of substances expressed as amounts in moles.

Melted and in the liquid state.

Melted into the liquid state.

The protective herb Hermes gives Odysseus to prevent Circe’s enchantment; it has a black root and a milk-white flower.

The turning effect of a force about a pivot, measured in newton-metres (Nm).

The turning effect of a force about a pivot: force multiplied by perpendicular distance from the pivot to the force’s line of action. Measured in newton metres (N m).

Switch operation that lasts only while the switch is held; releasing it restores its normal position.

The turning effect of a force about a pivot, measured in newton-metres (Nm).

The product of an object's mass and velocity, measured in kilograms metres per second (kg m/s). It has a direction because velocity has a direction.

The property of a moving object calculated using $p = mv$, where mass is measured in kilograms and velocity in metres per second. Momentum has a direction and is measured in kg m/s.

A change in momentum caused when a particle rebounds from a container wall.

A system of government in which a king or queen is the ruler.

A system of government headed by a king or queen.

A system with a king or queen as head of state.

A system in which the position of monarch is held by a king or queen.

A religious community of monks, or the buildings in which they live, worship and work.

A building where a community of monks lives, worships and follows religious vows.

A community whose members dedicate their lives to religious practices, particularly prayer and devotion to God.

Lanfranc’s regulations for monastic worship, responsibilities and training, issued around 1077.