Accuracy
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How close to the true value a measurement is.
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Acid
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A chemical that is a proton donor. Releases H+ (aq) in solution.
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Activation Energy
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The minimum energy required to start a reaction by breaking chemical bonds in the reactants.
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Aim
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Identifies the purpose of an investigation. What is trying to be found out.
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Alcohol
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A group of organic compounds with the functional group -OH.
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Alicyclic Hydrocarbon.
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Carbon atoms are joined in a ring structure.
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Alkali
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Soluble in water releasing OH- (aq) Ions.
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Alkanes
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Homologous series of saturated hydrocarbons.
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Alkenes
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A homologous series of unsaturated hydrocarbons.
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Amount of Substance
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The quantity whose unit is the mole. It is a way of counting atoms.
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Aliphatic Hydrocarbons
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A hydrocarbon where carbon atoms are joined together in straight or branched chains.
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Anhydrous
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A substance that contains no water molecules.
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Anion
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Negatively charged ion.
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Anomalies/ Anomalous
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Data that doesn't fit the particular trend of data and doesn't follow the general pattern.
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Aqueous
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A solution with water as the solvent.
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Aromatic Hydrocarbons
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Contain at least 1 benzene ring (ring of 6 carbons).
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Atom
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Composed of electrons and a central nucleus of protons and neutrons.
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Atomic Number
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The number of protons in the nucleus of an atom.
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Atomic Orbital
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A region of space where a maximum of 2 electrons with opposite spins in each can be found.
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Atomic Radius
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The distance from the nucleus to the boundary of the surrounding cloud of electrons.
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Average Bond Enthalpy
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The mean energy needed for 1 mole of a given type of gaseous bonds to undergo homolytic fission.
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Avogadro Constant
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The number of atoms per mole of the carbon-12 isotope = 6.02 X 10^23 mol^-1
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Base
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A chemical that can react with acids and is a proton acceptor.
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Biodegradable Materials
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Decompose by microorganisms and environmental conditions.
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Biological Catalysts
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Enzymes - Catalyse reactions in the body.
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Bioplastics
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Materials made from a renewable source that are biodegradable.
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Boltzmann Distribution
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The distribution of energies of molecules at a particular temperature, often shown as a graph.
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Bond Angle
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The angle that is formed between to adjacent bonds on the same atom.
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Bonded Pair
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A pair of electrons that have been shared between two chemically bonded atoms.
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Bonding Region
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The space where an electron can be found in a bond.
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Carbonyls
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An organic molecule which contains the C=O functional group.
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Carboxylic Acids
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An organic acid containing a carboxyl functional group –COOH.
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Calorimetry
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The quantitative study of energy change in a chemical reaction.
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Catalyst
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A substance that increases the rate of reaction by decreasing the activation energy. It is not used up in the process.
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Categoric Variable
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A qualitative description of a variable.
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Cation
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Positively charged ion.
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CFCs
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Chlorofluorocarbons are a class of organic compounds that are non-toxic to humans but can be radicalised by UV light.
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Chemical Energy
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A special form of potential energy stored in chemical bonds.
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Cis-Trans Isomerism
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A type of E/Z isomerism where two substituent groups on each carbon are the same.
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Collision Theory
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A model to help understand and make predictions about how changing factors may change the rate of a chemical reaction.
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Complete Combustion
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The oxidising of a fuel in a plentiful supply of oxygen.
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Compound
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A substance formed from 2 or more chemically bonded elements in a fixed ratio.
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Concentration Of A Solution
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The amount of solute dissolved per 1dm^3 of solution.
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Concordant Results
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Values that are close to each other and therefore represent reliable quantitative data.
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Continuous Variable
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A measured value which could be any number.
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Control Variable
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A factor that you must keep constant between experimental runs so that you can compare results.
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Covalent Bond
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A bond formed by a shared pair of electrons between 2 atoms nuclei.
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Curly Arrows
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Model the flow of electron pairs during reaction mechanisms.
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Dative Covalent Bond
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A bond formed by a shared pair of electrons that have been provided by one of the bonding atoms only.
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Dehydration
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A chemical reaction where a water molecule is eliminated from an organic compound.
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Delocalised Electrons
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Electrons that are shared between more than 2 atoms.
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Dependent Variable
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The factor that you observe in an experiment.
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Discrete Variables
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Variables that can only be particular defined numbers.
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Displacement Reactions
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A reaction in which a more reactive element takes the place of a less-reactive element in a compound.
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Displayed Formula
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A formula which Shows the relative positioning of atoms and the bonds between them.
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Disproportionation
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The oxidation and reduction of the same element in a redox reaction.
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Distillation
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A technique used to separate miscible liquids or solutions.
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Dot Formulae
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Gives the ratio between the number of compound molecules and the number of water molecules within the crystalline structure.
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Dynamic Equilibrium
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The equilibrium that exists in a closed system when the rate of the forwards reaction is equal to the rate of the backwards reaction and all the chemicals have a constant concentration.
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E/Z Isomerism
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A type of isomerism that is caused by the restricted rotation around the C=C where 2 different substituent groups are attached to each carbon atom.
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Electrical Conductivity
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The degree to which a specified material allows charge to be carried.
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Electron
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Carries a negative charge. Has a mass of 1/2000 and the number of electrons is equal to the number of protons.
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Electron Configuration
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The arrangement of electrons in an atom or ion.
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Electron Shielding
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The repulsion between electrons in different inner shells. Shielding reduces the net attractive force form the positive nucleus on the outer-shell electrons.
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Electronegativity
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A measure of the attraction of an electron in a covalent bond.
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Electrophile
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An electron-pair acceptor.
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Elimination
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An organic chemical reaction in which one reactant forms two products.
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Empirical Formula
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The simplest whole number ratio of atoms of each element present in a compound.
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Endothermic
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A reaction in which the enthalpy of the products is greater than the enthalpy of the reactants, resulting in heat being taken in from the surroundings.
Positive DeltaH.
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Enthalpy H
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The heat content that is stored in a chemical system.
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Enthalpy Change of Combustion
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The energy change that takes place when 1 mole of a substance is completely combusted.
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Enthalpy Change Of FormationT
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The energy change that takes place when 1 mole of a compound is formed from its constituent elements in their standard states under standard conditions.
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Enthalpy Change Of Neutralisation
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The energy change associated with the formation of 1 mole of water from a neutralisation reaction.
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Enthalpy Change Of Reaction
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The energy change associated with a given reaction.
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Enthalpy Cycle
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A pictorial representation showing alternative routes between reactants and products (Hess Law).
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Enthalpy Profile Diagrams
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A diagram of a reaction that allows you to compare the enthalpy of the reactants with the enthalpy of the products.
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Equilibrium Constant, Kc
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Kc shows the position of equilibrium. It Gives the measure of where the equilibrium lays.
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Equilibrium Law
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aA+bB⇌cC+dD
Kc= [C]c[D]d
[A]a[B]b
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Ester
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A functional group of –COO found in some organic molecules.
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Esterification
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The chemical reaction which forms an ester.
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Exothermic
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A reaction in which the enthalpy of the products is smaller than the enthalpy of the reactants, resulting in heat loss to the surroundings.
Negative DeltaH.
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Experiment
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An ordered set of practical steps which are used to test a hypothesis.
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Extraneous Variable
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A factor that is not controlled or measured in an experiment but may introduce error into the results.
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False Positive
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When a positive result is produced but not due to the desired product being formed.
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First Ionisation Energy
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The energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions.
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Fragmentation
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The process in mass spectrometry that causes a positive ion to split into pieces, one of which is a positive fragmented ion.
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Functional Group
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A group of atoms that is responsible for the characteristic chemical reactions of a compound.
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General Formula
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The simplest algebraic formula for a homologous series.
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Giant Covalent Lattice
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A 3D structure of atoms that are all bonded together by strong covalent bonds.
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Giant Ionic Lattice
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A 3D structure of oppositely charged ions held together by strong electrostatic forces of attraction.
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Giant Metallic Lattice
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A 3D structure of positive ions and delocalised electrons held together by metallic bonds.
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Global Warming
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The increased average temperature of the planet and atmosphere, thought to be caused by increase concentrations of Carbon Dioxide.
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Group
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A vertical column in the periodic table. Elements have similar chemical properties and their atoms have the same number of electrons in the outer shell.
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Halogenation
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An addition reaction where a halogen is added across the C=C.
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Haloalkanes
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A group of chemical compounds derived from alkanes, containing halogens.
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Hess' Law
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States that the enthalpy change in a chemical reaction is independent of the route it takes.
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Heterogeneous Catalyst
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A catalyst which is in a different phase from the reactant.
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Heterolytic Fission
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Happens when each bonding atom receives one electron from the bonded pair to form 2 radicals.
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Homogeneous Catalyst
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A catalyst which is in the same phase as the reactant.
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Homologous Series
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A series of organic compounds that have the same functional group with successive members differing by a CH2.
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Homolytic Fission
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Happens when one bonding atom receives both electrons from the bonding pair.
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Hydrated
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A crystalline compound containing water molecules.
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Hydration/Hydrolysis
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A reaction where water is a reactant.
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Hydrocarbons
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Compounds that contain only carbon and hydrogen atoms.
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Hydrogen Bond
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A strong permanent dipole-dipole attraction between an electron deficient H atom and a lone pair of electrons on O, N or F.
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Hydrogenation
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An addition reaction where hydrogen is added across the C=C.
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Hypothesis
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A prediction and explanation of the chemistry behind the prediction.
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