IGCSE Chemistry - Pearson Edexcel - GLOSSARY DEFINITIONS ONLY - COMPLETED Flashcards
FLASHCARDS MADE MYSELF WITH AID OF SOURCE BOOK: CHEMISTRY PEARSON EDEXCEL INTERNATIONAL GCSE (9-1) STUDENT BOOK BY JIM CLARK, STEVE OWEN AND RACHEL YU
What does absorb mean?
Take in (a gas or a liquid).
What is an acid?
A substance that acts as a source of hydrogen ions (H+) in solution (Arrhenius theory) or as a proton donor (Brønsted–Lowry theory).
What is acid rain?
Rain which has a pH of less than about 5.6. It is caused when water and oxygen in the atmosphere react with sulfur dioxide to produce sulfuric acid, or with various oxides of nitrogen (NO(x)) to give nitric acid.
What is activation energy?
The minimum amount of energy required for a collision to be successful, i.e. to result in a reaction.
What is an addition reaction?
A chemical reaction in which one molecule adds to another without taking anything away, to form a single product. For example, when alkenes react with halogens, the halogen atoms add onto the alkene molecule.
What is addition polymerisation?
Polymerisation of monomers containing a carbon-carbon double bond. A large number of monomer molecules add onto each other without anything else being formed.
What are alcohols?
A homologous series of compounds which all contain an -OH functional group attached to a hydrocarbon chain.
What are alkali metals?
Group 1 elements including lithium, sodium, potassium, rubidium, caesium and francium. NOTE: HYDROGEN IS NOT AN ALKALI METAL.
What are alkanes?
A homologous series of similar hydrocarbons in which all the carbons are joined to each other with single covalent bonds. These are saturated compounds with the general formula CnH2n+2.
What are alkanes?
A homologous series of similar hydrocarbons in which all the carbons are joined to each other with single covalent bonds. These are saturated compounds with the general formula CnH2n+2.
What are alkenes?
A homologous series of hydrocarbons which contain a carbon-carbon double bond. These are unsaturated compounds with the general formula CnH2n.
What are allotropes?
Different forms of the same element, for example diamond, graphite and C60 fullerene are three allotropes of carbon.
What is an alloy?
A mixture of metal with, usually, other metals or carbon. For example, brass is an alloy of copper and zinc, and steel is an alloy of iron and carbon.
What are amphoteric substances?
Substances that can react with both acids and bases to form salts.
What does anaerobic mean?
In the absence of air.
What does anhydrous mean?
Without water.
What is an anion?
A negative ion, formed by atoms gaining electrons.
What is the anode?
The positive electrode in electrolysis (Positive Anode Negative Is Cathode - PANIC) which attracts negative ions (anions).
What is an anomalous result?
A result that does not fit in with the pattern of the others.
What does aqueous mean?
Dissolved in water.
What is an array?
An ordered arrangement of things.
What is ash?
The soft powder that remains after something has been burned.
What is an atom?
The smallest piece of an element that can still be recognised as that element.
What is the atomic number of an atom?
The number of protons in an atom (also equal to the number of electrons in an atom).
What is Avogadro’s constant?
CONTEXT: 1 mol is the amount of substance that contains the same number of particles as there are atoms in 12.0 g of carbon-12.
ANSWER: Avogadro’s constant is the number of ^12C atoms in 12g of ^12C(6.02 x 10^23 mol^-1).
What is balancing an equation?
A process of putting coefficients in front of formulae so that the same number of atoms of each type is on both side of the equation.
What is the barrier method?
A method of rust prevention by coating iron with paint, oil, grease or plastic, so that oxygen/water cannot reach the iron/steel.
What is a base?
A substance that neutralises acids by combining with the hydrogen ions in them. They are usually metal oxides, hydroxides or ammonia. A soluble base is called an alkali, and it is a substance that acts as a source of hydroxide ions (OH-) in solution (Arrhenius theory) or as a proton acceptor (Brønsted–Lowry theory).
What is a batch?
A group of things that are produced or are dealt with together.
What is a biofuel?
A fuel that is made from biological sources, such as sugar cane or corn.
What is a biopolyester?
A polyester which is biodegradable.
What is bleach?
A chemical used to make something paler or whiter, or to sterilise something.
What is boiling?
The change of state from a liquid to a gas. It occurs at the boiling point.
What is bond energy?
The amount of energy required to break 1 mole of covalent bonds in gaseous molecules, or the amount of energy released when 1 mole of covalent bonds are formed in gaseous molecules.
What is a branch?
Something that grows out from the main part of an object.
What is bubbling?
Producing bubbles.
What is a bulb?
A glass object that produces light when electricity is passed through it. OR, the wider part of some plastic pipettes, which is squeezed to allow the pipette to be filled.
What is calorimetry?
Measuring the heat given out or taken in by a chemical reaction.
What are carboxylic acids?
A homologous series of compounds which all contain
a -COOH functional group attached to a hydrocarbon chain.
What is a catalyst?
A substance that speeds up a chemical reaction by providing an alternative pathway of lower activation energy. Catalysts are not used up and remain chemically unchanged at the end of the reaction.
What is a catalytic converter?
A device used in cars to convert oxides of nitrogen and carbon monoxide into harmless nitrogen gas and carbon dioxide. It uses platinum, palladium and rhodium as catalysts.
What is the cathode?
The negative electrode (Positive Anode Negative Is Cathode - PANIC) in electrolysis, which attracts positive ions (cations).
What is a cation?
A positive ion, formed by atoms losing electrons.
What are ‘chemical means’?
Methods which involve chemical reactions.
What is a chromatogram?
The absorbent paper from paper chromatography showing the separation of different coloured substances.
What is a clump?
A small group or cluster.
What is the coefficient?
The number written in front of formulae in a balanced chemical equation.
What is a coil?
A continuous series of circular rings into which something such as a wire or rope has been wound or twisted.
What is collision theory?
Collision theory states that for a reaction to occur, the reactant particles must collide with each other and the collision needs to have sufficient energy and the correct orientation.
What is combustion?
A chemical reaction in which a substance reacts with oxygen (burns) to form products and heat.
What is a competition reaction?
A displacement reaction between a more reactive metal and the oxide of a less reactive metal.
What is complete combustion?
Complete combustion occurs when a hydrocarbon burns in sufficient oxygen (burns) and forms carbon dioxide and water as products.
What is a compound?
A substance that forms when two or more elements chemically combine. The elements cannot be separated by physical means.
What is condensation?
The change of state from a gas to a liquid. It occurs at the condensation point.
What is condensation polymerisation?
Polymerisation of monomers in which each time two monomers combine, a small molecule such as water or hydrogen chloride is removed.
What is a corrosive substance?
A substance which can damage living tissue.
What is covalent bonding?
Strong electrostatic forces of attraction between the nuclei of the atoms making up the bond and the shared pair of electrons.
What is cracking?
A process in which long-chain alkanes are converted to alkenes and shorter-chain alkanes. It is carried out using silica or alumina as catalyst at a temperature of 600 - 700°C.
What is crude oil?
Formed from the remains of living organisms when their soft tissue was gradually changed by high pressure and high temperatures into a thick, black oil. Crude oil is a mixture of hydrocarbons.
What is crystallisation?
A process in which a solute (soluble solid) is obtained from its solvent.
What does damp mean?
Slightly wet.
What is a decomposition reaction?
A chemical reaction in which a compound is broken down into its elements or simpler compounds.
What does dehydration mean?
Removal of water.
What are delocalised electrons?
Electrons that are no longer attached to particular atoms or pairs of atoms, but are free to move throughout the whole structure.
What is a denatured enzyme?
An enzyme which has lost its function due to structural changes, usually caused by changes in temperature pH.
What is the dependant variable?
What you measure in an experiment.
What is deposition?
The change of state directly from a gas to solid.
What is a diatomic molecule?
A molecule that contains two atoms.
What is a condensation reaction?
A chemical reaction in which two molecules combine to form a larger molecule with elimination of a small molecule such as water.
What is diffusion?
The random movement of particles from an area of high concentration to an area of low concentration.
What does dimerise mean?
Forming a dimer - two identical molecules react to form a larger molecule.
What does dip mean?
To put something into a liquid and lift it out again.
What is a discharged ion?
An ion which loses its charge by losing or gaining electrons.
What is a displacement reaction?
A chemical reaction in which a more reactive element replaces a less reactive one in its compound.
What is a displayed formula?
A formula that shows all the bonds in a molecule as individual lines. Each line represents a pair of shared electrons in a covalent bond.
What is a dot-and-cross diagram?
A representation of how electrons are arranged in ions or molecules.
What is a double bond?
A double bond is where atoms share two pairs of electrons in a covalent bond.
What does drive off mean?
Force something to go away.
What is dry ice?
Solid carbon dioxide.
What does it mean to say metal is ductile?
Ductile is a property of metal which allows it to be drawn out into wires.
What is a dynamic equilibrium?
Equilibrium means the concentrations of the reactants and the products in a reversible reaction remain constant. Dynamic means the reactions are still continuing, but the rate of forward reaction is equal to the rate of the reverse reaction.
What is an electrode?
A conductor through which electricity is passed into and out of an electrolyte.
What is electrolysis?
The chemical change caused by passing an electric current through a compound that is either molten or in solution.
What is electrolyte?
A liquid that undergoes electrolysis. Electrolytes are molten ionic compounds or solutions containing ions.
What is an electrolytic cell?
A compartment in which electrolysis occurs.
What is an electron?
A subatomic particle found in shells (energy levels) outside the nucleus of an atom. It has a relative mass of 1/1836 and a relative charge of 1-. For a neutral atom, the number of electrons = number of protons = the atomic number.
What is electronic configuration?
How electrons are arranged in the shells (energy levels) of an atom.
What is electrostatic attraction?
The force of attraction between something that is positive and something that is negative.
What is an element?
A substance that cannot be split into anything simpler by chemical means. An element contains atoms of the same atomic number.
What does the empirical formula of an atom give?
The empirical formula gives the simplest whole number ratio of the atoms present in a compound. It can be worked out from experimental data.
What is the end point of titration?
The point at which the indicator changes colour.
What are endothermic reactions?
Reactions in which heat energy is taken in from the surroundings.
What is energetics?
The study of energy change in chemical reactions.
What is enthalpy change?
The amount of heat energy taken in or given out in a chemical reaction. It has the symbol ΔH.
What are enzymes?
Biological catalysts, usually consisting of proteins.
What are esters?
Esters are organic compounds formed by the reaction of an alcohol with a carboxylic acid. They have the functional group -COO-.
What is esterification?
A chemical reaction in which an alcohol and a carboxylic acid react together to form an ester.
What is evaporation?
The change of state from a liquid to a vapour. It occurs at a temperature below the boiling point and only at the surface of the liquid.
What is excess?
Having more than enough of a reactant to react with all of something else.
What are exothermic reactions?
Reactions in which heat energy is given out to the surroundings.
What does fade mean?
To lose colour and brightness.
What is fermentation?
Converting sugar such as glucose into ethanol and carbon dioxide using enzymes in yeasts.
What is the filtrate?
The liquid that comes through the filter paper during filtration.
What is filtration?
A process to separate an insoluble solid from a liquid.
What does fizz mean?
To make many bubbles, producing a continuous sound.
What does flake off mean?
Come off in small pieces.
What does flash mean?
Shine suddenly and brightly for a short period of time.
What does flush out mean?
Force something out.
What is a formula?
A representation of a chemical showing the elements present.
What is a forward reaction?
A reaction from reactants to products (the left-to-right reaction).
What are fossil fuels?
Fossil fuels include coal, gas and fuels derived from crude oil, which all come from things that were once alive.
What is fractional distillation?
A process to separate two liquids of similar boiling points, for example ethanol and water or the components of crude oil.