Topic 3- Periodic table and Energy Flashcards
groups
vertical row of elements in the periodic table
periods
horizontal row of elements in the periodic table
periodicity
a repeating trend in properties of the elements across each period of the periodic table
first ionisation energy
the energy required to remove one electron from each atom in one mole of gaseous atoms of an element to form one mole of gaseous 1+ ions
successive ionisation energy
metallic bonding
electrostatic attraction between positive metal ions and delocalised electrons
reducing agent
reduces another species by adding electrons
oxidising agent
oxidises another species by removing electrons
disproportionation
a redox reaction where the same element is oxidised and reduced simultaneously
enthalpy
the heat content that is stored in a chemical system
exothermic
a reaction where the enthalpy of the product is smaller than the enthalpy of the reactant, resulting in heat loss to the surroundings
endothermic
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
activation energy
minimum energy required to start a reaction by breaking the bonds
standard conditions
a pressure of 100kPa, a stated temperature, usually 298K, and a concentration of 1 moldm^-3
standard enthalpy change of reaction
the enthalpy change that accompanies a reaction in the molar quantities expressed in a chemical equation under standard conditions and in standard states
standard enthalpy change of formation
the enthalpy change that takes place 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 that takes place when one mole of a substance reacts completely with oxygen under standard conditions and standard states
standard enthalpy change of neutralisation
the enthalpy change that accompanies the reaction of an acid by a base to form one mole of water under standard conditions and in standard states
average bond enthalpy
energy required to break one mole of a specified bond in a gaseous molecule
catalyst
a substance that increases the rate of a chemical reaction without being used up.
Provides an alternate route with a lower activation energy.
homogenous catalyst
catalyst and the reactants are in the same state
heterogenous catalyst
catalyst in a different physical state to the reactants
dynamic equilibrium
equilibrium that exists in a closed system when the rate of the forward reaction is equal to the rate of the reverse reaction and concentrations do not change
le chateliers principle
when a system in dynamic equilibrium is subjected to a external change, the system readjusts itself to minimise the effect of the change and to restore equilibrium
