Periodic Table and Energy Flashcards
Periodicity*
the repeating pattern of trends in physical and chemical properties which occurs across different periods in the periodic table
First Ionisation Energy*
the energy required to remove one electron from each atom in one mole of gaseous atoms to form one mole of gaseous 1+ ions
Second Ionisation Energy
the energy required to remove one electron from each ion in one mole of gaseous 1+ ions to form one mole of gaseous 2+ ions
Disproportionation*
when a species is simultaneously oxidised and reduced to form two different products
Standard Enthalpy Change of Reaction
the enthalpy change when a reaction occurs in the molar quantities shown in the chemical equation under standard conditions
Standard Enthalpy Change of Formation*
the enthalpy change when one mole of a compound is formed from its constituent elements in their standard states under standard conditions
Standard Enthalpy Change of Combustion*
the enthalpy change when one mole of a substance is burned completely in oxygen under standard conditions
Standard Enthalpy of Neutralisation*
the enthalpy change when an acid reacts with an alkali to form one mole of water under standard conditions
Standard Conditions*
100kPa and 298K
Average Bond Enthalpy
the energy required to break one mole of the specified bond in gaseous molecules averaged over many different compounds
Exothermic Reaction
gives out energy, delta H is negative
Endothermic Reaction
takes in energy, delta H is positive
Activation Energy*
the minimum energy required for a reaction to occur
Hess’ Law
the total enthalpy change for a reaction is always the same, no matter which chemical route is taken
Catalyst*
a substance that speeds up a reaction without being used up by the overall reaction
Homogenous Catalyst
a catalyst which has the same physical state as the reactants
Heterogenous Catalyst
a catalyst which has a different physical state from the reactants
Dynamic Equilibrium*
a dynamic equilibrium exists in a closed system when the forward and reverse reactions are both occurring at the same rate, such that there is no overall change in the concentrations of the reactants or products
Le Chatelier’s Principle
when a system in dynamic equilibrium is subjected to a change, the equilibrium position will shift to minimise the change
