reactivity 1.2- HL

the heat energy change in a reaction at constant pressure

298K 100KPa

the energy needed to break a particular covalent bond

the average bond dissociation energy for a particular bond in a range of different compounds

heat energy change at constant pressure when one mole of a compound is formed from its elements in their standard states under standard conditions

heat energy released at constant pressure when one mole of an element of compound undergoes complete combustion under standard conditions

the total energy change in a reaction is independent of the route

theoretical insight into theroretical energy chabges associated with the formation of ionic solids, provide method of determining value of the lattice enthalpy of an ionic compound

metal is converted from a solid to a gas by breaking the metallic bonds holding the atom together (endothermic reaction) =enthalpy of combustion of your metal

simple covalent gas molecule is converted to atoms by breaking the covalent bond holding atoms together (endothermic) eg. CL2 -> Cl =bond enthalpy of your non metal

metal atoms are oxidised into metal ions, they lose electrons = first ionisation energy of metal (endothermic) sometimes needs more than one =second ionisation energy of your metal (endothermic) eg. Mg 2+

non metal atom, gains electrons lost by metal ion = first ionisation energy of your non metal (exothermic) sometimes gains more than one =second ionisation energy of your non metal (endothermic) non metal atoms are reduced into non metal ions

metal and non metal ions combine into a ionic lattic =lattice enthalpy of your ionic compound

to all the enthalpy energys of the born haber cycle added together

endo= upwards arrow exo= downward arrow

enthapy change when one mole of gaseous metal atoms are formed from the metal element at standard conditions (endothermic)

enthalpy chnage at constant pressure when one mole of an ionic compound is formed from its elements at standard states under standard conditions (exothermic)

enthalpy change when one mole of gasous non metal atoms gains an electron to form a mole of gasous negative non metal ions (exothermic)

enthalpy change when one mole of gasous non metal atoms are formed from the non metal elements in their standard states (endothermic)

enthalpy chnage when one mole of ionic copound is formed from gaseous non metal and metal ions

first is always exo the next to come are always endo

size of ions and charge of ions

the smaller the ions the more closely the ions can pack together and attract each other

the more charged is the ion the stronger the electrostatic force of attraction between them