Flashcards
Definitions in AS chemistry
Flashcards do conjunto (26)
- 1CatalystSubstance which speeds up a chemical reaction but is chemically unchanged at the end
- 2Hess's LawThe enthalpy change of a reaction is independent of the route taken
- 3Le Chatelier's PrincipleIf a factor affecting the equilibrium of a reversible reaction is changed, the position of equilibrium will shift in the direction which opposes that change.
- 4ElectronegativityThe power of an atom to withdraw electron density from a covalent bond
- 5Enthalpy changeChange in heat content at constant pressure
- 6EnthalpyA measure of the heat content of a substance
- 7Mean bond enthalpyThe enthalpy required to break a covalent bond, averaged over a wide range of compounds
- 8Standard enthalpy of combustionEnthalpy change when 1 mole of a substance is completely burned in oxygen with all reactants and products in standard states under standard conditions
- 9Standard enthalpy of formationEnthalpy change when 1 mole of a substance is formed from its constituent elements with all reactants and products in standard states under standard conditions.
- 10Relative atomic mass(average mass of one atom)/(mass of one atom of 12 C) x12
- 11Carbon neutralNo net carbon (dioxide) emissions to atmosphere
- 12HydrationThe addition of water to a molecule/compound.
- 13Structural isomerismCompounds which have the same molecular formula but different structural formulae
- 14Free radicalAtom or molecule with an unpaired electron
- 15Reducing agentA species that donates electrons
- 16OreA rock containing enough metal for extraction to be profitable
- 17Oxidising agentA species that gains electrons in a redox reaction
- 18ReductionGain of electrons
- 19OxidationLoss of electrons
- 20DisproportionationA redox reaction where some atoms of an element are oxidised and some atoms of the same element are reduced.
- 21Empirical formulaThe simplest ratio of the number of atoms of each element in a compound
- 22Molecular formulaThe number of atoms of each element in a molecule
- 23First ionisation energyEnergy needed to remove one mole of electrons from one mole of atoms in the gaseous state to form one mole of ions with a +1 charge
- 24Atomic numberThe number of protons in the nucleus of an atom
- 25Mass numberNumber of protons + number of neutrons
- 26Rate of reactionChange in concentration of a substance / reactant / product per unit time
Informações
- Descrição
- Definitions for AQA AS Chemistry, mostly taken directly from mark schemes.
- Criado por
- Stephen Cole
- Visualizações
- 404
- Tags
- Avaliação