igcse chemistry

acid

any substance that produces hydrogen ions, H+, when dissolved in water

acidic solution

a solution with a pH less than 7

acid rain

rain with a pH less than 5.6; acid rain has been made more acidic than normal rain because sulfur oxides and nitrogen oxides have dissolved in it; acid rain causes damage to buildings made from limestone, damages metal structures, kills fish, damages leaves in trees so they photosynthesise less

acidic soil

soil with a pH less than 7

activation energy

minimum amount of energy needed to start the reaction/for a successful collision.

actual yield

the amount of product obtained when carrying out a reaction

addition reaction

a reaction in which atoms are added to an unsaturated carbon compound; the atoms are added using the double bond as one of the double bonds breaks and is used to make two new bonds, e.g. alkenes and halogens

addition polymer

polymer formed by addition polymerization; adding many unsaturated monomers using double bonds

addition polymerization

the joining together of many unsaturated monomer molecules (double bonds) to form a long molecule; new monomers are added to the chain at the double bonds

alcohol

a homologous series of organic compounds which has -OH as its functional group; ethanol is a member of this homologous series

alkanes

a homologous series of hydrocarbons which are saturated as they have only single bonds between the carbon atoms

alkenes

a homologous series of hydrocarbons which are unsaturated as they have at least 1 double bond somewhere in the chain

allotrope

different forms of the same element e.g. diamond, graphite and the fullerenes are allotropes of carbon

alloys

mixture of a metal and small amounts of other metals and non-metals, made to have certain improved properties eg harder, stronger, increased resistance to corrosion, increased heat or electrical resistance

alkali

any base which is soluble in water

alkali metal

any metal in group 1 of the Periodic Table, most reactive metals

alkali solution

a solution with a pH larger than 7

anions

negative ions; attracted to anode

anode

positive electrode in electrolysis

arrangement

how particles are positioned compared to each other e.g. close together, far apart, in fixed positions

atom

the smallest particle that can exits of an element

atomic number

number of protons in the nucleus of an atom, determines the order and place of each element in the Periodic Table

avogadro's constant

6.02 x 1023

balanced equation

numbers of atoms are the same on either side of the equation (any equation should be balanced as in any chemical reaction particles are only re-arranged and are not destroyed or created); also shows the ratio in which reactants react and products are produced during a chemical reaction

base

a substance which can neutralise an acid to make a salt and water examples: metal oxides, metal hydroxides,

bauxite

ore containing aluminium oxide from which aluminium is extracted

blast furnace

a furnace used for getting iron from iron oxide with the help of carbon

boiling

a process during which a liquid changes into a gas as its particles gain more energy and move a lot faster and also much farther apart from each other. further from gas to liquid; only happens at the boiling temperature as opposed to evaporation

brine

concentrated sodium chloride solution

catalyst

a substance which speeds up a reaction but which remains unchanged at the end of the reaction

catalytic converter

a piece of equipment which is part of the exhaust of a car and which changes nitrogen oxides into nitrogen before they are released into the atmosphere

cathode

negative electrode in electrolysis

cation

positive ion ; attracted to cathode

chain length

number of carbon atoms one after the other in an organic compound

chemical bond

electrostatic attraction between atoms or ions

chemical property

how it reacts

chromatogram

the result of a chromatography

chromatography

a separating technique which uses the difference in solubility in a given solvent between the different parts of a mixture to separate them;

combustion

burning, the reacting of a substance with oxygen, exothermic

complete combustion

combustion in sufficient oxygen which in the case of hydrocarbons produces carbon dioxide and water

compound

a pure substance made from two or more different atoms joined together chemically

concentration

the number of moles of per liter of solution; tells us how much solute is dissolved inn a solvent

condensation

a process during which a gas changes into a liquid because its particles are having less energy, slow down and come much closer together

condensation polymer

a long molecule formed by condensation polymerization e.g. nylon

condensation polymerization

the joining together of many of two different monomer molecules to form one single long molecule during which a small molecule is removed for each link between the monomers.

covalent bond

force of attraction between a pair of shared electrons and the nucleii of both atoms

cracking

the breaking down of long-chain alkanes into smaller alkanes and alkenes using a catalyst and heat (500 C)

crude oil (or petroleum)

a mixture of organic compounds formed, as a result of high temperatures and pressures, from the remains of living plants and animals which died millions of years ago; a fossil fuel

crystallisation

the forming of crystals from a saturated solution

decomposition

breaking down a compound into simpler substances

delocalised electrons

electrons that can move between atoms; they are not part of 1 atom

diamine

diatomic

2 atoms only

dicarboxylic acid

diffusion

the movement of particles by which different substances mix as a result of the random motion of each of their particles

displacement reaction

a reaction in which a more reactive metal or halogen takes the place of a less reactive metal or halogen in its compound

distillate

the liquid obtained from distillation; the liquid which has evaporated and condensed

distillation

a separating technique in which a mixture is heated, the substance with the lowest boiling point evaporates and is condensed back to liquid form

ductile

can easily be drawn into wires, what metals are

endothermic

absorbs energy

electrical conductivity

conducts electricity for which it needs mobile charged particles

electrodes

rods of ususally carbon which are used to make elctrical contact with the electrolyte

electrolysis

a reaction which uses electricity to decompose a compound

electrolyte

an ionic compound or acid which conducts electricity (molten or in solution) and which is decomposed as it conducts

electrolytic cell

a beaker with an electrolyte, 2 electrodes, a power supply and leads which changes electrical energy into chemical energy

electron

a sub-atomic particle which has a negative charge and no relative mass

electronic configuration

the number of electrons on each energy level in an atom

element

a pure substance that consists of 1 type of atom only

empirical formula

the formula which gives the most simple ratio of atoms/ions in a molecule/formula unit

equilibrium

is reached when the forward reaction and reverse reaction are going on at the same time; at this point the amount of reactant or product does not change.

evaporation

a process during which a liquid changes into a gas as some of its particles at the surface gain more energy, move a lot faster and farther apart from each other and eventually escape from the liquid; happens at any temperature between melting and boiling point.

e

changing of particles at the surface from a liquid into a gas state; at any temperature between the melting and boiling point of a liquid.

exothermic

releases/gives out energy

fermentation

the changing of sugars dissolved in water into alcohol and carbon dioxide by the enzymes in yeast at a temperature of between 30 C to 40 C.

filtrate

the liquid/solution that goes through the filter paper

fixed positions

particles in a solid cannot move from their positions because of the strong forces of attraction

forces of attraction

forces which hold/pull particles together

forward reaction

the reaction which produces the products

fraction

a group of substances which has a specific boiling point/range/condenses at similar temperature (because they have a similar number of carbon atoms in them);

fractional distillation

crude oil is heated to evaporate most components which then condense back at different levels in the fractionating column because they have differing boiling points;

freezing

process during which a liquid changes into a solid as its particles lose energy, slow down and come closer together again

fuel

a substance that can release a lot of energy e.g. by burning

gas

a state of matter in which particles are far apart, have a lot of energy and move fast and randomly

galvanising

the coating of steel or iron by zinc to protect it from rusting

giant structure

a structure in which a very large number of atoms or ions are joined together strongly and continuously in all 3 directions; a large network of particles

group

vertical column in Periodic Table

half equation

equation showing what goes on at each electrode in electrolysis

halogen

any element from group 7 in the Periodic table

homologous series

a group of organic compounds which all have the same general formula, similar chemical properties because they have the same functional group, have a gradual trend in physical properties, and differ by one CH2 unit.

hydrocarbon

a compound which has carbon and hydrogen only

incomplete combustion

burning in not enough oxygen

indicator

any chemical which can change colour when added to different chemicals, usually acids and bases

inert

very unreactive

inert gases

gases in group 0

intermolecular forces

weak forces of attraction between molecules

ion

a charged atom or group of atoms (which has become charged because it has either lost or gained an electron(s))

ionic bond

strong electrostatic attraction between two oppositely charged ions, formed between metals and non-metals

isomers

compounds with the same molecular formula but different structures or displayed formula and therefore different properties

isotopes

atoms with the same number of protons and electrons but different number of neutrons; same mass number but different mass number

lattice

regular 3-dimensional arrangement of the particles (atoms, ions or molecules)