SOF NSO key terms

The property of a metal that lets it be hammered or rolled into thin sheets without breaking, as when aluminium becomes foil or gold becomes leaf.

The ability of a metal to be drawn out into long thin wires, which is why copper and aluminium are used for electrical wiring and cables.

The property of a metal that makes a ringing sound when struck, which is why metals such as brass are shaped into bells and gongs.

A material that allows heat or electric current to pass through it easily, usually because it contains freely moving electrons; most metals behave this way.

A material that resists the flow of heat or electric current, such as rubber, plastic, glass, or dry wood, and is used to shield and handle conductors safely.

A solid mixture made by melting two or more elements together, at least one of them a metal, to obtain properties better than the pure metal, such as steel or brass.

An alloy in which mercury is one of the components; dental filling material and the mercury–silver mixture used in old mirrors are familiar examples.

The slow wearing away of a metal by reaction with substances around it, such as the rusting of iron in moist air or the greening of copper.

A method of protecting iron from rusting by coating it with a thin layer of zinc, which corrodes in preference to the iron beneath it.

A bond formed when two atoms share one or more pairs of electrons, typical of the bonds holding carbon atoms together in diamond, graphite, and organic compounds.

One of two or more different structural forms of the same element in the same physical state, such as diamond, graphite, and fullerene for carbon.

A molecular form of carbon in which the atoms are arranged in closed cage shapes, the best known being the 60-atom football-shaped molecule called buckminsterfullerene.

A family of carbon compounds with the same general formula and functional group, in which successive members differ by one CH2 unit and show gradually changing properties.

The particular atom or group of atoms attached to a carbon chain that gives a compound its characteristic reactions, such as –OH in alcohols or –COOH in carboxylic acids.

One of two or more compounds that have the same molecular formula but different arrangements of atoms, and therefore different physical or chemical properties.

The reaction between a carboxylic acid and an alcohol, usually warmed with a little acid catalyst, that produces an ester plus water; esters often smell fruity.

The alkaline breakdown of an ester, especially a fat or oil, by heating with sodium hydroxide to give soap and glycerol.

Asexual reproduction in plants in which a new individual grows from a part of the parent such as a root, stem, leaf, or bud, giving offspring identical to the parent.

The transfer of pollen grains from the anther of a flower to the stigma, either within the same flower or between flowers, as a step before fertilisation.

The fusion of a male gamete with a female gamete to form a zygote, which is the first cell of a new individual in sexual reproduction.

The temporary organ in the uterus through which a developing embryo receives nutrients and oxygen from the mother's blood and passes out wastes.

The ability of some organisms, such as Hydra and planaria, to regrow a complete body from a detached piece of tissue after it is cut.

A form of asexual reproduction in which a small outgrowth of the parent body develops into a new individual and then separates, as in yeast and Hydra.

The statement that, at constant temperature, the current through a metallic conductor is directly proportional to the potential difference across its ends, so V equals IR.

The property of a conductor that opposes the flow of electric current, measured in ohms; it depends on material, length, thickness, and temperature.

A characteristic constant of a material, equal to the resistance of a conductor of that material having unit length and unit cross-sectional area; its unit is the ohm metre.

A circuit in which components are joined end to end so that the same current passes through each of them and the total voltage divides among them.

A circuit in which components are connected across the same two points, so each receives the full supply voltage and the total current splits between the branches.

The rate at which electrical energy is transferred or consumed in a device, equal to voltage multiplied by current and measured in watts.

The region around a magnet or a current-carrying conductor in which a magnetic force can be detected on another magnet or on a moving charge.

A long coil of insulated wire wound in a cylinder shape; when current flows, the field inside is uniform and the coil behaves like a bar magnet.

A temporary magnet made by winding a coil around a soft iron core and passing current through it; its strength can be varied and it loses magnetism when the current stops.

A rule for finding the direction of the force on a current-carrying conductor in a magnetic field, using the thumb, forefinger, and middle finger held at right angles.

A rapid, automatic response to a stimulus that is completed through a reflex arc in the spinal cord without waiting for the brain to decide.

The structural and functional unit of the nervous system, a cell specialised to receive, carry, and pass on electrical impulses to other cells.

The tiny gap between two neurons or between a neuron and a target cell, across which a chemical messenger carries the impulse onward.

A chemical messenger secreted in small amounts by an endocrine gland into the blood and carried to a target organ, where it regulates a specific body process.

A logical relationship question that presents one pair of items connected by a rule and asks you to find a second pair linked by the same rule.

A reasoning task in which a sequence of numbers, letters, or figures follows a hidden rule, and the next or missing element must be identified.

A classification question in which all items but one share a common property, and the item that does not fit that property must be selected.