Chapter 19: Lattice Energy Flashcards
Lattice energy
Enthalpy change when 1 mole of an ionic compound is formed from its gaseous ions under standard conditions
Enthalpy change of atomisation
The enthalpy change when 1 mole of gaseous atoms is formed from its element under standard conditions
Electron affinity
The first electron affinity, is the enthalpy change when 1 mole of electrons is added to 1 mole of gaseous atoms to form 1 mole of gaseous 1- ions under standard conditions
The second electron affinity
The enthalpy change when 1 mole of electrons is added to 1 mole of gaseous 1- ions to form 1 mole of gaseous 2- ions under standard conditions
Converting solid atoms to gas atoms
Atomisation
Convert gas atoms to gas ions
1st ionization
Convert molecules to atoms
Atomisation
How does size affect lattice energy
Larger radius with the same charge have lower charge density because charge is spread over a larger area making the lattice energy less exothermic
How does charge affect lattice energy
Greater charge in anions and ions, attract each other more strongly. Ions of similar size but greater ionic charge results in higher charge density and stronger ionic bonds
Ion polarization
Distortion of electron cloud on anion by cation
Polarizing power
Ability of cation to attract electrons and distort anion
Degree of polarization of an anion
Charge density of the cation and polarisibility, ease at which it can be polarized
How is an anion more likely to be polarized
Cation is small with a charge of +2 or 3 and anion is big with a charge of -2 or 3
Enthalpy change of hydration
When 1 mole of a specified gaseous ions dissolves in sufficient water to form a very dilute solution
Enthalpy change of solution
Energy absorbed or released when 1 mole of an ionic solid dissolves in sufficient water to form a very dilute solution
