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Chemistry AS Definitions

taylora27 Chemistry AS - Level English 149 cards

Cards in this deck (149)

  1. 1AcidA species that is a proton donor.
  2. 2Activation EnergyThe minimum energy required to start a reaction by breaking the bonds.
  3. 3Addition PolymerA very long molecular chain formed by repeated addition reactions of many unsaturated alkene molecules/monomers.
  4. 4Addition PolymerisationThe process in which unsaturated alkene molecules add on to a growing polymer chain one at a time to form a very long saturated molecular chain.
  5. 5Addition ReactionA reaction in which a reactant is added to an unsaturated molecule to make a saturated molecule.
  6. 6AdsorptionThe process that occurs when a gas, liquid or solute is held to the surface if a solid, or more rarely, a liquid.
  7. 7Alicyclic hydrocarbonA hydrocarbon with carbon atoms joined together in a ring structure.
  8. 8Aliphatic hydrocarbonA hydrocarbon with carbon atoms joined together in straight or branched chains.
  9. 9AlkaliA type of base that dissolves in water forming hydroxide ions, OH- (aq) ions.
  10. 10AlkanesThe homologous series with the general formula: CnH2n+2
  11. 11Alkyl groupAn alkane with a hydrogen atom removed, often shown as 'R'.
  12. 12Amount of substanceThe quantity whose unit is the mole. Chemists use 'amount of substance' as a means of counting atoms.
  13. 13AnhydrousA substance that contains no water molecules.
  14. 14AnionA negatively charged ion.
  15. 15Atom Economy(molecular mass of desired product / sum of molecular masses of all products) x 100
  16. 16Atomic orbitalA region within an atom that can hold up to 2 electrons, with opposite spins.
  17. 17Atomic (proton) numberThe number of protons in the nucleus of an atom.
  18. 18Average Bond EnthalpyThe average enthalpy change that takes place when breaking by homolytic fission 1 mol of a given type of bond in the molecules of a gaseous species.
  19. 19Avogadro constant, NAThe number of atoms per mole of the carbon-12 isotope (6.02 x10^23)
  20. 20BaseA species that is a proton acceptor.
  21. 21Biodegradable materialA substance that is broken down naturally in the environment by living organisms.
  22. 22Boltzmann distributionThe distribution of energies of molecules at a particular temperature, usually shown on a graph.
  23. 23Bond EnthalpyThe enthalpy change that takes place when breaking by homolytic fission 1 mol of a given bond in the molecules of a gaseous species.
  24. 24CarbanionAn organic ion in which a carbon atom has a negative charge.
  25. 25CarbocationAn organic ion in which a carbon atom has a positive charge.
  26. 26CatalystA substance that increases the rate of a chemical reaction without being used up in the process.
  27. 27CationA positively charged ion.
  28. 28Cis-trans isomerismA special type of E/Z isomerism in which there is a non-hydrogen group and a hydrogen atom of each C of a C=C double bond: the cis-isomer (Z isomer) has the H atoms on each carbon on the same side; the trans-isomer (E isomer) has the H atoms on each carbon on different sides of the bond.
  29. 29CompoundA substance formed from 2 or more chemically bonded elements in a fixed ratio, usually shown by a chemical formula.
  30. 30ConcentrationThe amount of solute, in mol, per 1 dm^3 (1000 cm^3) of solution.
  31. 31Coordinate bondA shared pair of electron which has been provided by one of the bonding atoms only; also called a dative covalent bond.
  32. 32CrackingThe breaking down of long-chained saturated hydrocarbons to form a mixture of shorter-chained alkanes and alkenes.
  33. 33Curly arrowA symbol used in reaction mechanisms to show the movement of an electron pair in the breaking or formation of a covalent bond.
  34. 34Dative covalentA shared pair of electrons which has been provided by one of the bonding atoms only; also called a coordinate bond.
  35. 35DehydrationAn elimination reaction in which water is removed from a saturated molecule to make an unsaturated molecule.
  36. 36Delocalised electronsElectrons that are shared between more than two atoms
  37. 37Displacement reactionA reaction in which a more reactive element displaces a less reactive element from an aqueous solution of the latter's ions.
  38. 38Displayed formulaA formula showing the relative positioning of all the atoms in a molecule and the bonds between them
  39. 39Dynamic equilibriumThe equilibrium that exists in a closed system where the rate of the forward reaction is equal to the rate of the reverse reaction.
  40. 40E/Z isomerismA type of stereoisomerism in which different groups attached to each carbon of a C=C double bond may be arranged differently in space because of the restricted rotation of the C=C bond.
  41. 41Electron configurationThe arrangement of electrons in an atom.
  42. 42ElectronegativityA measure of the attraction of a bonded atom for the pair of electrons in a covalent bond.
  43. 43Electron shieldingThe repulsion between electrons in different inner shells. Shielding reduces the net attractive force from the positive nucleus on the outer-shell electrons.
  44. 44ElectrophileAn atom (or group of atoms) that is attracted to an electron-rich centre of atom, where it accepts a pair of electrons to form a new covalent bond.
  45. 45Elimination reactionThe removal of a molecule from a saturated molecule to make an unsaturated molecule.
  46. 46Empirical formulaThe simplest whole-number ration of atoms of each element present in a compound.
  47. 47Endothermic reactionA 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 (delta H +ve)
  48. 48Enthalpy, HThe heat content that is stored in a chemical system.
  49. 49(standard) enthalpy change of combustionThe 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.
  50. 50(standard) enthalpy change of formationThe enthalpy change that takes place when one mole of a compound is formed from its constituent elements in their standard states and under standard conditions.
  51. 51(standard) enthalpy change of reactionThe 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.
  52. 52Enthalpy cycleA diagram showing alternative routes between reactants and products which allows the indirect determination of an enthalpy change from other known enthalpy changes using Hess's Law.
  53. 53Enthalpy profile diagramA diagram for a reaction to compare the enthalpy of the reactants with the enthalpy of the products.
  54. 54EsterificationThe reaction of an alcohol with a carboxylic acid to produce an ester and water.
  55. 55Exothermic reactionA reaction in which the enthalpy of the products is smaller than the enthalpy of the reactants, resulting in heat loss to the surroundings (delta H -ve).
  56. 56Fractional distillationThe 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.
  57. 57FragmentationThe process in mass spectrometry that causes a positive ion to split into pieces, one of which is a positive fragment ion.
  58. 58Functional GroupThe part of the organic molecule responsible for its chemical reactions.
  59. 59General FormulaThe simplest algebraic formula of a member of a homologous series. For example, the general formula of the alkanes is CnH2n+2.
  60. 60Giant covalent latticeA three-dimensional structure of atoms, bonded together by strong covalent bonds.
  61. 61Giant ionic latticeA three-dimensional structure of oppositely charged ions, bonded together by strong ionic bonds.
  62. 62Giant metallic latticeA three-dimensional structure of positive ions and delocalised electrons, bonded together by strong metallic bonds.
  63. 63Greenhouse EffectThe process in which the absorption and subsequent emission of infrared radiation by atmospheric gases warms the lower atmosphere and the planet's surface.
  64. 64GroupA vertical column in the Periodic Table. Elements in a group have similar chemical properties and their atoms have the same number of outer shell electrons.
  65. 65Hess's LawIf a reaction can take place by more than one route and the initial and final conditions are the same, the total enthalpy change is the same for each route.
  66. 66Heterogeneous catalystA reaction in which the catalyst has a different physical state from the reactants; frequently, reactants are gases whilst the catalyst is a solid.
  67. 67Heterolytic fissionThe breaking of a covalent bond with both of the bonded electrons going to one of the atoms, forming a cation and an anion.
  68. 68Homogeneous catalystA reaction in which the catalyst and reactants are in the same physical state, which is most frequently the aqueous or gaseous state.
  69. 69Homolytic fissionThe breaking of a covalent bond with one of the bonded electrons going to each atom, forming 2 radicals.
  70. 70Homologous seriesA series of organic compounds with the same functional group, but with each successive member differing by CH2.
  71. 71HydratedCrystalline and containing water molecules
  72. 72HydrocarbonA compound of hydrogen and carbon only.
  73. 73Hydrogen BondA strong dipole-dipole attraction between an electron-deficient hydrogen atom (O-H* or N-H*) on one molecule and a lone pair of electrons on a highly electronegative atom (H-O* or H-N*) on a different molecule.
  74. 74HydrolysisA reaction with water or aqueous hydroxide ions that breaks a chemical compound into two compounds.
  75. 75InitiationThe first step in a radical substitution in which the free radicals are generated by ultraviolet radiation.
  76. 76Intermolecular forceAn attractive force between neighbouring molecules. Intermolecular forces can be induced dipole-dipole forces, permanent dipole-dipole forces or hydrogen bonds.
  77. 77IonA positively or negatively charged atom or (covalently bonded) group of atoms (a molecular ion).
  78. 78Ionic bondingThe electrostatic attraction between oppositely charged ions.
  79. 79(first) ionisation energyThe energy required to remove one mole of electrons from one mole of gaseous atoms.
  80. 80(second) ionisation energyThe energy required to remove one electron from each ion in one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions.
  81. 81(successive) ionisation energyA measure of the energy required to remove each electron in turn.
  82. 82IsotopesAtoms of the same element with different numbers of neutrons and different masses.
  83. 83Le Chatelier's principleWhen a system in dynamic equilibrium is subjected to a change, the position of equilibrium will shift to minimise the change.
  84. 84Limiting reagentThe substance in a chemical reaction that runs out first.
  85. 85Lone pairAn outer-shell pair of electrons that is not involved in chemical bonding.
  86. 86Mass (nucleon) numberThe number of particles (protons and neutrons) in the nucleus.
  87. 87MechanismA sequence of steps showing the path taken by electrons in a reaction.
  88. 88Metallic bondThe electrostatic attraction between positive metal ions and delocalised electrons.
  89. 89Molar mass, MThe mass mole of a substance. The units of molar mass are g mol-1.
  90. 90Molar volumeThe volume per mole of a gas. The units of molar volume are dm^3 mol-1. At room temperature and pressure the molar volume is approx. 24.0 dm^3 mol-1.
  91. 91MoleThe amount of any substance containing as many particles as there are carbon atoms in exactly 12g of the carbon-12 isotope.
  92. 92Molecular formulaThe number of atoms of each element in a molecule.
  93. 93Molecular ion, M+The positive ion formed in mass spectrometry when a molecule loses an electron.
  94. 94MoleculeA small group of atoms held together by covalent bonds.
  95. 95MonomerA small molecule that combines with many other monomers to form a polymer.
  96. 96NomenclatureA system of naming compounds.
  97. 97NucleophileAn 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.
  98. 98Nucleophilic SubstitutionA type of substitution reaction in which a nucleophile is attracted to an electron-deficient centre or atom, where it donates a pair of electrons to form a new covalent bond.
  99. 99OxidationLoss of electrons or an increase in oxidation number.
  100. 100Oxidation numberA measure of the number of electrons that an atom uses to bond with atoms of another element. Oxidation numbers are derived from a set of rules.
  101. 101Oxidising agentA reagent that oxides (takes electrons from) another species.
  102. 102Percentage yield(Actual amount, in mol, of product / theoretical amount, in mol, or product) x100
  103. 103PeriodA horizontal row of elements in the Periodic Table. Elements show trends in properties across a period.
  104. 104PeriodicityA regular periodic variation of properties of elements with atomic number and position in the Periodic Table.
  105. 105Permanent dipoleA small charge difference across a bond resulting from a difference in electronegativities of the bonded atoms.
  106. 106Pi- bondThe reactive part of a double bond formed above and below the plan of the bonded atoms by sideways overlap of p-obitals.
  107. 107Polar covalent bondA bond with a permanent dipole.
  108. 108Polar moleculeA molecule with an overall dipole, taking into account any dipoles across bonds.
  109. 109PolymerA long molecular chain built up from monomer units.
  110. 110Precipitation reactionThe formation of a solid from a solution during a chemical reaction. Precipitates are often formed when two aqueous solutions are mixed together.
  111. 111Principal quantum number, nA number representing the relative overall energy of each orbital, which increases with distance from the nucleus. The sets of orbitals with the same n value are referred to as electron shells or energy levels.
  112. 112PropagationThe two repeated steps in radical substitution that build up the products in a chain reaction.
  113. 113RadicalA species with an unpaired electron.
  114. 114Rate of reactionThe change in concentration of a reactant or a product in a given time.
  115. 115Redox reactionA reaction in which both reduction and oxidation take place.
  116. 116Reducing agentA reagent that reduces (adds electrons to) another species.
  117. 117ReductionGain of electrons or a decrease in oxidation number.
  118. 118RefluxThe continual boiling and condensing of a reaction mixture to ensure that the reaction takes place without the content of the flask boiling dry.
  119. 119Relative atomic mass, ArThe weighted mean mass of an atom of an element compared with 1/12th of the mass of an atom of carbon-12.
  120. 120Relative formula massThe weighted mean mass of a formula unit compared with 1/12th off the mass of an atom of carbon-12.
  121. 121Relative isotopic massThe mass of an atom of an isotope compared with 1/12th of the mass of an atom of carbon-12.
  122. 122Relative molecular mass, MrThe weighted mean mass of a molecule compared with 1/12th of the mass of an atom of carbon-12.
  123. 123Repeat unitA specific arrangement of atoms that occurs in the structure over and over again. Repeat units are included in brackets, outside of which is the symbol n.
  124. 124SaltA chemical compound formed from an acid, when a H+ ion from the acid has been replaced by a metal ion or another positive ion, such as the ammonium ion, NH4+.
  125. 125Saturated hydrocarbonA hydrocarbon with single bonds only.
  126. 126ShellA group of atomic orbitals with the same principal quantum number, n. Also known as a main energy level.
  127. 127Simple molecular latticeA three-dimensional structure of molecules, bonded together by weak intermolecular forces.
  128. 128Skeletal formulaA simplified organic formula, with hydrogen atoms removed from alkyl chains, leaving just a carbon skeleton and associated functional groups.
  129. 129SpeciesAny type of particle that takes part in a chemical reaction.
  130. 130Specific heat capacity, cThe energy required to raise the temperature of 1g of a substance by 1 degree celsius.
  131. 131Spectator ionsIons that are present but take no part in a chemical reaction.
  132. 132Standard conditionsA pressure of 100kPa (1 atmosphere), a stated temperature, usually 298K (25'C), and a concentration of 1mol dm-3 (for reactions with aqueous solutions).
  133. 133Standard enthalpiesSee enthalpy.
  134. 134Standard solutionA solution of known concentration. Standard solutions are normally used in titrations to determine unknown information about another substance.
  135. 135Standard stateThe physical state of a substance under the standard conditions of 100kPa, and 298K.
  136. 136StereoisomersCompounds with the same structural formula but with a different arrangement of the atoms in space.
  137. 137StoichiometryThe molar relationship between the relative quantities of substances taking part in a reaction.
  138. 138StratosphereThe second layer of the Earth's atmosphere, containing the 'ozone layer', about 10km to 50km above the Earth's surface.
  139. 139Structural formulaA formula showing the minimal detail for the arrangement of atoms in a molecule.
  140. 140Structural isomersMolecules with the same molecular formula but with different structural arrangement of atoms.
  141. 141Sub-shellA group of the same type of atomic orbitals (s,p,d or f) within a shell.
  142. 142Substitution reactionA reaction in which an atom or group of atoms is replaced with a different atom or group of atoms.
  143. 143TerminationThe step at the end of a radical substitution when two radicals combine to form a molecule.
  144. 144Thermal decompositionThe breaking up of a chemical substance with heat into a least two chemical substances.
  145. 145TroposphereThe lowest layer of the Earth's atmosphere, extending from the Earth's surface up to about 7km (above the poles) and to about 20 km (above the tropics).
  146. 146Unsaturated hydrocarbonA hydrocarbon containing carbon-to-carbon multiple bonds.
  147. 147Van de Waal's forces (induced dipole-dipole interactions)Very weak attractive forces between induced dipoles in neighbouring molecules.
  148. 148VolatilityThe ease that a liquid turns into a gas. Volatility increases as boiling point decreases.
  149. 149Water of crystallisationWater molecules that form an essential part of the crystalline structure of a compound.

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AS - Level Chemistry Flashcards on Chemistry AS Definitions , created by taylora27 on 31/03/2016.
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