OCR F322 Heineman – Flashcards
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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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| Molecular Formula |
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| The actual number of atoms of each element in a molecule |
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| General Formula |
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| The simplest algebraic formula of a member of a homologous series. For example, the general formula of the alkanes is CnH2n+2 |
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| Structural Formula |
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| Shows the minimal detail for the arrangement of atoms in a molecule |
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| Displayed Formula |
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| Shows the relative positioning of all the atoms in a molecule and the bonds between them |
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| Skeletal Formula |
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| A simplified organic formula, with hydrogen atoms removed from alkyl chains, leaving just a carbon skeleton and associated functional groups |
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| Homologous Series |
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| A series of organic compounds with the same functional group but with each successive member differing by CH2 |
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| Functional Group |
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| The part of the organic molecule responsible for its chemical reactions |
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| Structural Isomers |
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| Molecules with the same molecular formula but with different structural arrangements of atoms |
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| Stereoisomers |
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| Compounds with the same structural formula, but with a different arrangement of the atoms in space |
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| E/Z Isomerism |
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| An example of stereoisomerism, in terms of restricted rotation about a double bond and the requirement for two different groups to be attached to each carbon atom of the C=C group |
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| Cis-Trans Isomerism |
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| A special type of E/Z isomerism in which two of the substituent groups are the same |
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| Hydrocarbons |
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| Organic compounds that contain carbon and hydrogen only |
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| Saturated Hydrocarbon |
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| A hydrocarbon with single bonds only |
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| Unsaturated Hydrocarbon |
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| A hydrocarbon containing carbon-to-carbon multiple bonds |
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| Aliphatic Hydrocarbon |
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| A hydrocarbon with carbon atoms joined together in straight or branched chains |
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| Alicyclic Hydrocarbon |
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| A hydrocarbon with carbon atoms joined together in a ring structure |
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| Alkanes |
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| The homologous series with the general formula: CnH2n+2 |
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| Nomenclature |
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| A system of naming compounds |
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| Alkyl Group |
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| An alkane with a hydrogen atom removed, e.g. CH3, C2H5; Aany alkyl group is often shown as R |
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| Homolytic Fission |
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| The breaking of a covalent bond, with each of the bonded electrons going to each atom, forming two radicals. |
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| Radical |
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| A species with an unpaired electron. |
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| Heterolytic Fission |
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| The breaking of a covalent bond with both of the bonded electrons going to one of the atoms, forming a cation (+ ion) and an anion (- ion) |
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| Nucleophile |
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| An atom (or group of atoms) that is attracted to an electron-deficient centre or atom, where it donates a pair of electrons to form a new covalent bond |
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| Electrophile |
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| An atom (or group of atoms) that is attracted to an electron rich centre or atom, where it accepts a pair of electrons to form a new covalent bond |
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| Addition Reaction |
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| A reaction in which a reactant is added to an unsaturated molecule to make a saturated molecule |
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| Substitution Reaction |
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| A reaction in which an atom or group of atoms is replaced with a different atom or group of atoms In a substitution reaction: 2 reactants ---> 2 products |
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| Elimination Reaction |
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| Refers to the removal of a molecule from a saturated molecule to make an unsaturated molecule In an elimination reaction: 1 reactant ---> 2 products |
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| Fractional Distillation |
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| The separation of the components in a liquid mixture into fractions which differ in boiling point (and hence chemical composition) by means of distillation, typically using a fractionating column |
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| Cracking |
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| Refers to the breaking down of long-chained saturated hydrocarbons to form a mixture of shorter-chained alkanes and alkenes |
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| Catalyst |
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| A substance that increases the rate of a chemical reaction without being used up in the process |
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| Radical Substitution |
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| A type of substitution reaction in which a radical replaces a different atom or group of atoms |
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| Mechanism |
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| A sequence of steps showing the path taken by electrons in a reaction |
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| Initiation |
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| The first step in a radical substitution in which the free radicals are generated by Ultraviolet Radiation |
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| Propagation |
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| The two repeated steps in radical substitution that build up the products in a chain reaction |
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| Termination |
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| The step at the end of a radical substitution when two radicals combine to form a molecule |
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| Pi-bond (? bond) |
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| The reactive part of a double bond formed above and below the plane of the bonded atoms by sideways overlap of p-orbitals |
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| Electrophilic addition |
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| A type of addition reaction in which an electrophile is attracted to an electron deficient centre or atom, where it accepts a pair of electrons to form a new covalent bond |
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| Carbocation |
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| An organic ion in which a carbon atom has a positive charge |
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| Curly Arrow |
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| A symbol used in reaction mechanisms to show the movement of an electron pair in the breaking or formation of a covalent bond |
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| Polymer |
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| A long molecular chain built up from monomer units |
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| Monomer |
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| A small molecule that combines with many other monomers to form a polymer |
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| Addition polymerisation |
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| The process in which unsaturated alkene molecules (monomers) add on to a growing polymer chain one at a time to form a very long saturated molecular chain (the addition polymer) |
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| Atom Economy |
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| {Molecular Mass of the desired products/ Sum of molecular masses of all products} X 100 |
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| Activation Energy |
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| The minimum energy required to start a reaction by the breaking of bonds |
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| Standard Conditions |
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| A pressure of 100 kPa (1 atmosphere), a stated temperature, usually 298K (25C), and a concentration of 1 mol dm^-3 (for reactions with aqueous solutions) |
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| Enthalpy change of reaction |
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| The enthalpy change that accompanies a reaction in the molar quantities expressed in a chemical equation under standard conditions, all reactants and products being in their standard states |
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| Enthalpy change of Formation |
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| The enthalpy change that takes place when one mole of a compound in its standard state is formed from its constituent elements in their standard states under standard conditions |
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| Enthalpy change of combustion |
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| The enthalpy change that takes place when one mole of a substance reacts completely with oxygen under standard conditions, all reactants and products being in their standard states |
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| Exothermic reaction |
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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 (?H -ve) |
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| Endothermic reaction |
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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 (?H +ve) |
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| Average bond enthalpy |
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| The average enthalpy change that takes place when breaking by homolytic fission 1 mol of a give type of bond in the molecules of a gaseous species |
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| le Chatelier's principle |
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| When a system in dynamic equilibrium is subjected to a change, the position of equilibrium will shift to minimise the change |
