3.1.8 Thermodynamics (A- Level only)

The energy transferred when 1 mole of the compound is formed from its elements under standard conditions in their standard states

Lattice enthalpy can be defined as either enthalpy of lattice dissociation or enthalpy of lattice formation

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

The enthalpy change required to remove 1 mole of electrons from 1 mole of gaseous atoms to form 1 mole of gaseous ions with a +1 charge

the enthalpy change to remove 1 mole of electrons from one mole of gaseous 1+ ions to produces one mole of gaseous 2+ ions

The first electron affinity is the enthalpy change that occurs when 1 mole of gaseous atoms gain 1 mole of electrons to form 1 mole of gaseous ions with a –1 charge

• first electron affinity is exo for atoms that normally form negative ions. • cus the ion is more stable than the atom, and there is an attraction between the nucleus and the electron.

the enthalpy change when one mole of gaseous 1- ions gains one electron per ion to produce gaseous 2- ion

• The second electron affinity for oxygen is endo - cus it takes energy to overcome the repulsive force between the negative ion and the electron