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Chemistry Glossary

For further information see Wikipedia.

Absolute zero – the coldest temperature possible, -273.15 °C, or 0 kelvin (0 K). 0 °C is 273.15 K.

Alloy – a combination of two or more elements, at least one of which is a metal, and where the resulting material has metallic properties, for example steel. The properties of the alloy (apart from being metallic) may be quite different from the properties of the elements that go into it. For example, the silver coloured coins we use (for a short while before they're phased out) are 75% copper, but not at all copper coloured themselves.

Aluminium – a lightweight metal, symbol Al, atomic number 13. See Chapter 15 – aluminium.

Black powder – a type of gunpowder, composed of (by mass) 75% saltpetre (potassium nitrate) 15% softwood charcoal (carbon), and 10% sulphur. See Chapter 3 – sulphur and carbon, and Chapter 13 – nitrogen and explosives.

Boiling chips – small chips of ceramic or similar material that are added to a test tube to make smoother boiling. Wikipedia says boiling chips are small, irregularly shaped stones added to liquids to make them boil more smoothly. They provide nucleation sites so the liquid boils easily without becoming superheated. Without boiling chips, a liquid heated in a smooth container can become superheated and "bump" in a sudden, sometimes violent release of vapor. This sudden burp of gas can cause the solution and reagents to be thrown out of the container, possibly causing severe burns, ruining an experiment, or simply making a mess.

Bronze – an alloy made from 60% copper and 40% tin.

Caesium – a very reactive metal, its pale yellow colour makes it one of only three coloured metals (along with copper and gold). See Chapter 7 – new elements.

Carbon – a non-metallic element, symbol C, atomic number 6. Carbon has two well known natural forms – graphite and diamond. Graphite is used in pencils, mixed with varying amounts of clay for varying hardness (which gives HB, 3B etc). Diamond is the hardest known natural mineral. See Chapter 3 – carbon.

Compound – a substance that is a chemically bonded combination of two or more different elements in a fixed ratio.

Copper – a soft orange-red coloured metal, symbol Cu (from Latin "cuprum"), atomic number 29. It is in the same family as silver and gold. See Chapter 2 – copper.

Diamond – a naturally occuring form of carbon. See Chapter 3 – carbon.

Ductile – means a substance can be pulled and stretched without ripping. For example, ductile metals can easily be drawn out into wires. Gold, copper, and aluminium are highly ductile metals. Also see malleable.

Electrum – an alloy of gold and silver with trace amounts of copper and other materials.

Element – a substance that cannot be decomposed or transformed into other chemical substances by ordinary chemical processes.

Family – a column from the periodic table. Also called a group.

Gold – a metal element, symbol Au (from Latin "aurum"), atomic number 79. It is in the same family as copper and silver. See Chapter 2 – gold.

Group – a column from the periodic table. Also called a family.

Helium – an inert (or noble) gas, symbol He, atomic number 2. See Chapter 7 – new elements.

Inert – a compound which doesn't react with anything.

Inorganic compound – a chemical compound which does not contain both carbon and hydrogen.

Insoluble – the material will not dissolve in water.

Iron – a metal element, symbol Fe (from Latin "ferrum" ), atomic number 26. See Chapter 1 – iron.

Isomer – compounds that have the same chemical formula but have the atoms arranged differently, eg a straight chain of carbon atoms and a branched chain with the same number of carbon atoms.

Isotope – elements with the same number of protons (atomic number) but differing numbers of neutrons. Some isotopes are more radioactive than others, eg C12 and C14.

Lead – a dense metal element, symbol Pb (from Latin "plumbum"), atomic number 82. See Chapter 1 – lead.

Legume – a type of plant that includes alfalfa, beans, clover, lentils, lupins, peanuts and peas,. Legumes are particularly special because they have bacteria around their root nodules that can fix nitrogen from the air. This means legumes can be used in a crop rotation to replenish soil that has been depleted of nitrogen.

Malleable – able to be easily deformed. Gold is the most malleable metal, followed by aluminium. Also see ductile.

Metal – an element that easily forms positive ions and has metallic bonds. The metallic bond accounts for many physical characteristics of metals, such as strength, malleability, ductility, conduction of heat and electricity, and lustre.

Meteor – a small rock (or sometimes lump of iron) that passes through Earth's atmosphere leaving a glowing trail. See Chapter 1 – iron.

Meteorite – a meteor that makes it all the way through the atmosphere without burning up and thus hits Earth's surface. See Chapter 1 – iron.

Methyl orange – acid/base indicater. Changes colour as a mid-strength acid, and is red below pH 3.1 and yellow-orange above pH 4.4. See Acid-Base Indicators.

Muriatic acid – the old name for hydrochloric acid.

Nitrogen – a colourless odorless gas that makes up most of out atmosphere, symbol N, atomic number 7. See Chapter 4 – nitrogen.

Oil of Vitriol – the old name for sulphuric acid (also called sulfuric acid). Pure sulphuric acid is a viscous clear liquid, like oil. See Acids & Bases.

Ore – rock which contains minerals which make it worthwhile for mining.

Organic compound – a chemical compound containing both carbon and hydrogen.

Oxidation – the combination of a material with oxygen. Burning is one kind of oxidation. An explosion is very rapid oxidation.

Paramagnetic – a material which becomes magnetic when in a magnetic field but doesn't become permanently magnetised (eg, our new coins).

Periodic Table – a tabular method for displaying the chemical elements. See the Periodic Table page.

Phosphorus – a non-metal element, symbol P, atomic number 15. See Chapter 3 – phosphorus.

Photon – a packet of light. Each photon has a particular energy, which determines its colour.

Pipette – a device that allows the user to extract or deliver small amounts of a liquid. Pipettes come in a variety of designs. Some are graduated to deliver exact quantities, but most allow for a "drop at a time" delivery.

Plutonium – a radioactive metal, symbol Pu, atomic number 94. Best known for its proclivity to undergo nuclear fission chain reactions, making it a potent fuel for nuclear weapons and power plants. Plutonium is one of the most unusual metals – it's not magnetic and it does not conduct electricity well. The material also changes its size dramatically with even the slightest changes in its temperature and pressure. The atom's unusual set of properties distinguishes it from even its closest neighbors on the periodic table, such as americium. (From The American Institute of Physics Bulletin of Physics News, update 817.)

Quenching – heating up iron until it is red hot then suddenly cooling it by putting it into cold water.

Silver – a metal element, symbol Ag (from Latin "argentum"), atomic number 47. It is in the same family as copper and gold. See Chapter 2 – silver.

Sodium vapour lamp – come in two varieties, high pressure and low pressure. A low pressure sodium vapour lamp has a distinctive yellow/orange colour because the light comes from the D1 and D2 spectral lines (see Chapter 7 – spectral lines). Low pressure sodium vapour lamps have horrible colour-rendering but the highest efficiency of any common lighting method, 27% (ie, 73% of the input energy is wasted as heat) which compares well with the efficiency of a normal 40W incandescent light bulb. It's just 1.9%. High pressure sodium lamps are smaller and contain some other elements (for example, mercury), produce a dark pink glow when first struck, and produce a pinkish orange light when warmed up.

Steel – a combination of iron with a small amount of carbon. See Chapter 1 – iron.

Sulphur – a non-metal element, symbol S, atomic number 16. Also spelled sulfur. See Chapter 3 – sulphur.

Tin – a metal element, symbol Sn, (from Latin "stannum"), atomic number 50. See Chapter 1 – tin.