Chemkeywords

	A
	Ar	short for relative atomic mass
	acid, acidic	a solution that has a pH of less than 7; it will neutralise an alkali
	acid rain	rain with nitrogen oxides or sulphur dioxide dissolved in it, which make the rain acidic
	alcohol	a substance produced by fermentation
	alkali, alkaline	a solution that has a pH of more than 7; it will neutralise an acid
	alkali metals	soft, reactive metals such as potassium and sodium in Group 1 of the Periodic Table; they react with water to produce alkaline solutions
	alloy	a mixture of metals
	aluminium	a lightweight metal extracted from its ore by electrolysis
	ammonia	a gas made from hydrogen and nitrogen by the Haber Process
	ammonium nitrate	a fertiliser made by neutralising nitric acid with ammonia
	aqueous	dissolved in water
	(aq)	short for aqueous; used in symbol equations
	atom	the smallest particle of an element
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	B
	basalt	an extrusive igneous rock containing small crystals
	bauxite	aluminium ore; an oxide
	blast furnace	used to extract iron from its ore
	boiling point	the temperature at which a liquid boils (when a liquid turns to a gas)
	brass	an alloy of copper and zinc
	brittle	brittle materials break or crumble when you hit them; the opposite of tough
	bromine	the only non-metal element that is a liquid at room temperature
	bronze	an alloy of copper and tin
	burn	when a substance reacts with oxygen and releases heat
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	C
	calcium	a reactive metal found in limestone
	calcium carbonate	the chemical name for limestone
	calcium hydroxide	the chemical name for slaked lime
	calcium oxide	the chemical name for quicklime
	carbon	a non-metal element found in the molecules of living things and fossil fuels
	carbon dioxide	a gas produced when substances containing carbon burn
	carbon monoxide	a toxic gas produced when there isn't enough oxygen for carbon to burn completely
	catalysts	substances that increase the rates (or speeds) of chemical reactions
	cement	made from limestone and clay; used to make concrete
	chlorides	salts made from hydrochloric acid
	chlorine	a toxic gas; a halogen in Group 7 of the Periodic Table
	coke	a form of carbon used in a blast furnace
	compound	a substance made from atoms of different elements joined together
	concentrated solution	a solution with a lot of dissolved substance in it
	concrete	artificial stone made using cement, gravel, sand and water
	condense, condensation	when a gas is changed to a liquid by cooling
	conductor	a substance that lets electricity pass through it; also used for conductors of heat
	copper	a useful, not very reactive metal
	core	the part of the Earth nearest the centre
	corrosive substances	substances such as acids that dissolve or eat away other materials
	cracking	splitting large hydrocarbon molecules into smaller ones
	crude oil	a liquid mixture of hydrocarbons found in the Earth's crust
	crust	the outside layer of the Earth, made from solid rock
	cryolite	added to bauxite to make it melt easier
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	D
	decompose	when a compound is split up into simpler substances
	diamond	a very hard form of carbon
	dilute solution	a weak solution, containing a lot of water
	displace, displacement	when one element is pushed out of one of its compounds by another element
	distil, distillation	when a liquid is evaporated and then condensed again
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	E
	electrodes	the places where the products form during electrolysis
	electrolysis	when a dissolved or molten compound is decomposed by having an electric current passed through it
	electronic structure	the arrangement of electrons of atoms into different energy levels
	electrons	particles with a negative electrical charge and very little mass, which surround the nucleus of an atom
	element	a substance that is made of only one type of atom
	endothermic	describes a chemical reaction that takes in energy from its surroundings
	enzymes	catalysts that are found in living cells
	evaporate, evaporation	when a liquid is changed into a gas or vapour
	exothermic	describes a chemical reaction that gives out energy to its surroundings
	extrusive rocks	igneous rocks formed outside the Earth's crust, eg. basalt
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	F
	ferment, fermentation	a reaction in which yeast produces alcohol and carbon dioxide from sugar
	fertilisers	substances put into soil to make crops grow better
	flammable substances	substances that catch fire easily
	formula	a collection of symbols and numbers that tells you the number of atoms of each element in a compound
	fossil fuels	fuels formed in the Earth's crust from the remains of living things, eg. oil
	fossils	the remains in rocks of plants or animals from long ago
	fraction	a part of a mixture of liquids separated by fractional distillation
	freeze, freezing	when a liquid changes to a solid by cooling
	fuels	substances we burn to release energy
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	G
	gases	substances that spread out to fill all the space they can; one of the states of matter
	(g)	short for gas; used in symbol equations
	gneiss	a metamorphic rock
	gold	a rare, unreactive metal found as the metal itself in the Earth's crust
	granite	an intrusive igneous rock containing large crystals
	graphite	a form of carbon that is a conductor of electricity
	greenhouse gases	gases in the air that make the Earth warmer, eg. carbon dioxide
	Group	a family of similar elements in the same column of the Periodic Table
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	H
	Haber Process	a process for making ammonia from hydrogen and nitrogen
	halides	compounds of metals with halogens, eg. chlorides
	halogens	reactive non-metal elements such as chlorine and bromine in Group 7 of the Periodic Table
	hard materials	hard materials don't get scratched or wear away easily
	hazard symbols	hazard symbols tell you if substances are dangerous, eg. toxic or flammable symbols
	hydrocarbons	compounds containing the elements hydrogen and carbon only; crude oil is a mixture of hydrocarbons
	hydrochloric acid	an acid that is produced by dissolving hydrogen chloride in water; this acid makes salts called chlorides
	hydrogen	a gas that burns with a squeaky 'pop'; its atoms are smallest of all
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	I
	igneous rock	rocks that form when molten magma or lava cools down
	indicators	substances with colours that depend on the pH of the solution they are in
	intrusive rocks	igneous rocks that are formed inside the Earth's crust, eg. granite
	ionic compounds	compounds made from ions
	ions	atoms that have gained or lost electrons and so have a negative or positive charge
	iron	a common metal; steel contains mainly iron
	isotopes	atoms of the same element that have different numbers of neutrons and so have different mass numbers
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	J
	K
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	L
	lava	molten rock from below the Earth' crust that has flowed out on to the surface
	limestone	a common sedimentary rock with many uses; its chemical name is calcium carbonate
	liquids	substances that have a definite volume but take the shape of the container in which you put them; one of the states of matter
	(l)	short for liquid; used in symbol equations
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	M
	Mr	short for relative molar mass
	magma	molten rock below the Earth's crust
	magnesium	a reactive metal
	mantle	the part of the Earth between the crust and the core
	marble	a metamorphic rock formed from limestone
	mass number	the total number of neutrons and protons in the nucleus of an atom
	melt, melting	when a solid changes into a liquid from a solid
	melting point	the temperature at which a solid melts
	mercury	the only element that is a liquid metal at room temperature
	metals	elements that are tough and conduct electricity
	metamorphic rock	rock formed from another type of rock when it is heated and put under high pressure in the Earth's crust
	mixture	a mixture contains different substances that are not chemically joined together
	molecular compound	a compound made from atoms of different elements, sharing electrons to form molecules
	molecule	a molecule contains atoms that are joined together by sharing electrons
	molten substance	a substance that has been melted
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	N
	neutral solution	a solution that is neither acidic nor alkaline; it has a pH of 7
	neutralise, neutralisation	when an acid and an alkali react to make a neutral solution
	neutrons	particles in the nucleus of an atom that have no electrical charge; they have the same mass as protons
	nitrates	salts produced from nitric acid; an important part of fertilisers
	nitric acid	an acid made by reacting ammonia with oxygen; this acid can be used to produce salts called nitrates
	nitrogen	a not very reactive gas that makes up about 80% of the air
	nitrogen oxides	compounds of nitrogen and oxygen that cause acid rain
	noble gases	unreactive gases in Group 0 of the Periodic Table
	non-metal	elements that are not metals
	nucleus	the central part of an atom, made of protons and neutrons
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	O
	oil	see crude oil
	ore	a compound from which a metal is extracted; often and oxide
	oxides	compounds of oxygen and another element
	oxygen	a gas that makes up about 20% of the air; it reacts with many other elements to form oxides
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	P
	particles	the very small bits that scientists think everything is made of
	Periodic Table	a table of the elements that has similar elements placed in the same column or Group
	pH	a scale that tells you how acidic or alkaline a solution is
	plastics	compounds made from oil; they are also called polymers
	polymers	substances such as plastics made from very long molecules
	potassium	a very reactive alkali metal
	products	the substances that are made in chemical reactions
	properties	what substances are like, eg. reactive or unreactive, brittle or tough
	proton number	the number of protons in an atom
	protons	particles found in the nucleus of an atom that have a positive electrical charge; they have the same mass as neutrons
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	Q
	quicklime	a substance made by heating limestone; its chemical name is calcium oxide
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	R
	rate of reaction	how fast a reaction happens
	reactants	the substances you start off with in a chemical reaction
	reactivity series	a list of elements in order of how reactive they are
	reduce, reduction	the process of obtaining a metal from its ore
	relative atomic mass	the mass of an atom compared to other atoms
	relative molecular mass	you get this by adding together the relative atomic masses of all the atoms in the formula of a compound
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	S
	salt (1)	a compound you get when you neutralise an acid with an alkali
	salt (2)	the everyday name for common salt or sodium chloride
	sandstone	a sedimentary rock made from grains of sand
	schist	a metamorphic rock
	sediment	small bits of solid that settle at the bottom of a liquid
	sedimentary rocks	rocks formed from layers of sediment
	silver halides	compounds of silver and a halogen
	slag	the molten waste produced in a blast furnace
	slaked lime	a substance used to make soil less acidic; its chemical name is calcium hydroxide
	slate	a metamorphic rock made from mudstone
	sodium	a very reactive alkali metal
	sodium hydroxide	a strong alkali that is used to make many other chemicals
	solder	an alloy of tin and lead
	solids	substances that keep their shape; one of the states of matter
	(s)	short for solid; used in symbol equations
	solute	a substance that is dissolved in a solvent to make a solution
	solution	a mixture formed when a substance is dissolved in water
	solvent	the liquid in which a solute is dissolved to form a solution
	stainless steel	an alloy of steel that does not rust
	state	describes whether a substance is a solid, a liquid or a gas, or dissolved in water
	state symbol	a short way of writing the state of a substance
	steel	a cheap, strong, useful alloy, made mainly of iron
	stiffness	stiff things don't bend easily
	strength	strong materials don't break easily when you pull them or squeeze them
	sulphates	salts made from sulphuric acid
	sulphur	a yellow, non-metal element
	symbol	a short way of writing an element, eg. carbon = C
	symbol equation	this shows the reactants and the products in a chemical reaction using their formulas
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	T
	tectonic plates	very large pieces of the Earth's crust, which move slowly on the molten magme beneath them
	toughness	a tough material doesn't break or crumble when you hit it; the opposite of brittle
	toxic substances	these substances are poisonous
	transition elements	metals in the central block of the Periodic Table; they do not belong to Groups 0 to 7
	U
	universal indicator	an indicator that has many different colours depending on the pH of the solution it is in
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	V
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	W
	water	a compound of hydrogen and oxygen; it is often used to dissolve solutes to make a solution
	word equation	this shows the reactants and the products of a chemical reaction using their names
	X
	Y
	Z
	zinc	a fairly reactive metal
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