module 3/5 Flashcards
What is periodicity?
a repeated trend in properties of elements across periods in the periodic table
Define ‘First Ionisation Energy’
Give an example
to remove 1 mole of electrons from 1 mole of gaseous atoms (to form 1 mole of gaseous 1+ ions) e.g. Mg(g) → Mg+(g) + e–
Define ‘Average Bond Enthalpy’
Give an example
The enthalpy required to break 1 mole of covalent bonds in the gaseous state e.g. ¼ CH4(g) → ¼ C(g) + H(g)
Define ‘ Enthalpy of formation’
The enthalpy required to make 1 mole of compound from elements e.g. Mg(s) + ½ O2(g) →MgO(s)
Define ‘Enthalpy of combustion’
The enthalpy change required to react 1 mole of a substance fully with oxygen / in excess oxygen e.g. CH3OH(g) + 1½ O2(g) - CO2(g) + 2 H2O(l)
Define ‘Neutralisation Enthalpy’
The enthalpy change required to form 1 mole of water when acid and alkali/base react e.g. HCl(aq) + NaOH(aq) à NaCl(aq) + H2O(l) or H+(aq) + OH–(aq) à H2O(l)
What are the ‘standard state conditions’?
298 K / 25 oC 1 atm / 100 kPa / 100,000 Pa all solutions 1.0 mol dm-3
Define ‘Lattice Enthalpy’
The enthalpy change required to form 1 mole of an ionic lattice from ions in the gaseous state e.g. Mg2+(g) + 2 Cl–(g) -> MgCl2(s)
Define ‘ Atomisation’
to form 1 mole of gaseous atoms from its element e.g. Mg(s) -> Mg(g)
Define ‘First Electron Affinity’
to form 1 mole of gaseous 1- ions from 1 mole of gaseous atoms (by adding 1 mole of electrons) e.g. Cl(g) + e– -> Cl–(g)
Define ‘solution Enthalpy’
The enthalpy change required to dissolve 1 mole of a substance in excess water e.g. MgCl2(s) -> MgCl2(aq)
Define ‘ Hydration Enthalpy’
The enthalpy change required to change 1 mole of gaseous ions into 1 mole of aqueous ions e.g. Mg2+(g) -> Mg2+(aq)
Define ‘Entropy’
the disorder within a substance / system
Define ‘Activation energy’
minimum energy needed by particles to react
Define ‘Catalyst’
speeds up a chemical reaction not used up, / is regenerated in the reaction, provides an alternative pathway for the reaction to proceed, provides a different lower activation energy Ec.
Define ‘Hetreogenous’
in different states
Define ‘Homogenous’
in the same state
Define ‘Half-life’
the time is takes for the concentration of a reactant to halve
Define ‘Rate-determining step’
the slowest step in a multi-step mechanism
Define ‘Dynamic Equilbrium’
forward and back reaction occur at the same rate concentrations of reactants/products do not change closed system
Define ‘Acid’
proton donor
Define ‘Base’
proton acceptor
Define ‘Alkali’
soluble base (produces OH–(aq))
Define ‘Strong Acid’
fully dissociates in solution e.g. HNO3(aq) -> H+(aq) + NO3–(aq) (has no Ka / pKa value)
