A Level Edexcel Chemistry - Topic 13 - Energetics 2/II

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Topic 13 - Energetics 2
Lattice Energy
Define the starndard lattice energy

is the energy change when 1 mole of an ionic solid is formed from its
gaseous ions under standard conditions

What is lattice energy the measure of?

its a measure of ionic bond strength

the more negative the lattice energy, the stronger the bonding

Describe the factors affecting lattice energy

the higher the charge on the ions, the more energy is released when an
ionic lattice forms, this is due to stronger electrostatic forces between ions

more energy released means the lattice energy will be more negative

so lattice energy for compounds with 2+ ions or 2- ions will be more
exothermic than those with 1+ or 1- ions

the smaller the ionic radii of the ions the more exothermic the lattice energy,
smaller ions have a higher charge density and their smaller ionic radii means
that the ions can sit closly together in the lattice, thereofore attractions between
ions are stonger



What is the enthalpy change of atomisation

the enthalpy change of atomisation is the enthalpy change when 1 mole of
gaseous atoms is formed from the element in its standard state

What is the first electron affinity




Topic 13 - Energetics 2 1

, the first electron affinity is the enthalpy change when 1 mole of electrons are
added to 1 mole of neutral gaseous atoms to form 1 mole of gaseous 1- ions

Draw a born haber cycle to calculate the lattice energy of NaCl




How would you calculate a value of lattice energy using the born harber cycle
above?




Draw a born haber cycle to calculate the lattice energy of MgCl2




Topic 13 - Energetics 2 2