179 terms

iGCSE Chemistry Edexcel Keywords


Terms in this set (...)

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
a homologous series of organic compounds which has -OH as its functional group; ethanol is a member of this homologous series
a homologous series of hydrocarbons which are saturated as they have only single bonds between the carbon atoms
a homologous series of hydrocarbons which are unsaturated as they have at least 1 double bond somewhere in the chain
different forms of the same element e.g. diamond, graphite and the fullerenes are allotropes of carbon
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
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
negative ions; attracted to anode
positive electrode in electrolysis
how particles are positioned compared to each other e.g. close together, far apart, in fixed positions
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
a substance which can neutralise an acid to make a salt and water examples: metal oxides, metal hydroxides,
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
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
concentrated sodium chloride solution
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
negative electrode in electrolysis
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
the result of a chromatography
a separating technique which uses the difference in solubility in a given solvent between the different parts of a mixture to separate them;
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
a pure substance made from two or more different atoms joined together chemically
the number of moles of per liter of solution; tells us how much solute is dissolved inn a solvent
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
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
the forming of crystals from a saturated solution
breaking down a compound into simpler substances
delocalised electrons
electrons that can move between atoms; they are not part of 1 atom
2 atoms only
dicarboxylic acid
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
the liquid obtained from distillation; the liquid which has evaporated and condensed
a separating technique in which a mixture is heated, the substance with the lowest boiling point evaporates and is condensed back to liquid form
can easily be drawn into wires, what metals are
absorbs energy
electrical conductivity
conducts electricity for which it needs mobile charged particles
rods of ususally carbon which are used to make elctrical contact with the electrolyte
a reaction which uses electricity to decompose a compound
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
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
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
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.
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.
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.
releases/gives out energy
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.
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
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;
process during which a liquid changes into a solid as its particles lose energy, slow down and come closer together again
a substance that can release a lot of energy e.g. by burning
a state of matter in which particles are far apart, have a lot of energy and move fast and randomly
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
vertical column in Periodic Table
half equation
equation showing what goes on at each electrode in electrolysis
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.
a compound which has carbon and hydrogen only
incomplete combustion
burning in not enough oxygen
any chemical which can change colour when added to different chemicals, usually acids and bases
very unreactive
inert gases
gases in group 0
intermolecular forces
weak forces of attraction between molecules
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
compounds with the same molecular formula but different structures or displayed formula and therefore different properties
atoms with the same number of protons and electrons but different number of neutrons; same mass number but different mass number
regular 3-dimensional arrangement of the particles (atoms, ions or molecules)
calcium carbonate
a state of matter in which particles are close together but in a disorderly arrangement, they can move past one another and have energy to move from their positions
an oily but soft substance used to reduce friction between two moving surfaces
easily shaped without breaking, what metals are
mass number
the total number of protons and neutrons in the nucleus of an atom
a process during which a solid changes into a liquid as its particles have gained more energy and move from their positions and past one another into an irregular arrangment
metallic bond
attraction between positive metal ions and delocalised (mobile 'sea' of electrons electrons
metallic character
behaves like a metal, gives away electron (s) when it reacts to form a positive ion, conducts, shiny, malleable
2 or more substances mixed together which have not reacted and which are therefore easily separated by physical processes like evaporation/distillation/filtration
molar mass
the actual mass of 1 mole or 6.02 x 1023 particles (atoms, ions, molecules or formula units) of that substance
molar volume
the volume of 1 mole of a gas = 24L at rtp
the name given to a certain number and that number is 6.02 x 1023.
molecular formula
shows the type of atoms/ions and their number/molar ratio in a molecule/formula unit
a particle made up of 2 or more atoms held together by covalent bonds
a small molecule which can be joined together to make a long molecule called a polymer; a monomer must have a double bond or a functional group at either end
how particles move e.g. fast, vibrate
a sub-atomic particle with no charge and which is in the nucleus and has a relative mass of 1
a reaction between an acid and a base to produce water and a salt and sometimes also carbon dioxide
noble gas
any element form the last group in the Periodic Table
noble gas electronic configuration
the way in which electrons are arranged in the noble gas atoms which is that they have their outer shell full! This 2 electrons in the helium atom and 8 in the other noble gases
a mixture of rock which contains a useful chemical
organic compounds
compounds that have the element CARBON in it
a reaction during which a substance gains oxygen; oxygen is added to the element or compound increasing its mass; also a reaction during which a substance loses an electron
a compound which ends with oxygen
oxidizing agent
a chemical which oxidises another chemical; it loses oxygen/gains electrons and becomes reduced
oxide layer
layer of an oxygen compound
% yield
the actual yield expressed as percentage of the theoretical yield
horizontal row in the Periodic Table
periodic trends
gradual changes in properties of the elements in the same period
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; contains fossil fuels.
a number between 1 and 14 which tells us how strong or how weak an acid or alkali is
pH scale
a scale running from 1- 14 used to show how acid or alkaline a substance is
physical property
properties like melting and boiling point, volatility, conductivity, appearance, colour
polymer made from polymerising ethene molecules - addition polymer
a large molecule made from many small molecules that have been joined together; each polymer is made up of many repeated units
a chemical reaction in which many small molecules or monomers are joined together to form a long molecule called a polymer
position of equilibrium
gives an idea of how much reactant or product there is at equilibrium
a reaction between 2 salt solutions which produces an insoluble salt which sinks to the bottom of the test tube
insoluble solid formed during a reaction
substance on right hand of equation
pure substance
a single chemical element or compound which melts and boils at fixed temperatures
rate of a reaction
amount of change in a reactant or product over a period of time; tells us how fast a reaction is going
substance on left side of equation
refers to the ease with which a substance reacts with other substances
reactivity series
a list of metals with the most reactive metal first based on results from experiments
a reaction during which both a chemical is oxidised and another is reduced
reducing agent
a chemcial which reduces another chemical; it gains oxygen/loses electrons and becomes oxidised
a reaction during which a susbstance loses oxygen and has its mass decreases; also a reaction during which a substance gains electrons
relative atomic mass
the mass of an atom as compared to 1/12th of the mass of a carbon-12 atom; it is also the average mass of all isotopes
relative molecular mass
the sum of the relative atomic masses (multiplied by the number of times they are in the molecule) of the atoms in the molecule
relative formula mass
the sum of the relative atomic masses (multiplied by the number of times they are in the formula) of the atoms or ions in the giant structure
the insoluble part that remains behind in the filter paper during a filtration or what is left in the flask
reverse reaction
reaction which changes products back into reactants
reversible reaction
a reaction during which products are made but are also changed back again into reactants
a loose orange brownflaky layer of hydrated iron oxide
sacrificial protection
method of rust protection in which blocks of more reactive metal are attached to irn; the more reactive metal react with the air and water instead of the iron
saturated solution
a solution which contains as much solute as possible
saturated organic compound
each carbon atom in the organic compound has made 4 single covalent bonds
simple molecular substance
substance made up of individual molecules held together by covalent bonds and has weak intermolecular forces between these molecules
a state of matter in which particles are close together and in a regular arrangement, can only vibrate in fixed positions and have little energy
a liquid that does the dissolving
solvent front
the height the solvent goes up to on the chromatography paper
a solid which dissolves
a mixture made by dissolving a solute in a solvent
an alloy of iron with other elements
sub-atomic particle
very small particles from which atoms are made: electrons, protons and neutrons
a process during which a solid changes directly into a gas because its particles have alot more energy, move around very fast and are very far apart.
the reactants and products of a reaction
theoretical yield
the amount of product you should obtain according to the balanced equation and calculations
thermal decomposition
breaking down of a compound by hetaing it
transition element
metal in the transition block of the Periodic Table
universal indicator
a mixture of indicators used to measure the pH because it goes different colours
unsaturated organic compound
has at least one double bond; decolourizes brown bromine water
the combining power of an atom or group of atoms; in an ionic compound the valency of an ion is its charge; in a molecule the valency of an atom is the number of bonds it makes
valency electrons
the electrons on the most outer shell;
change from liquid into gas
move forwards and backwards but in the same fixed position
vapourises easily, low boiling point
word equation
an equation in which the names of the chemicals are used