lattice energy?

[akcapr]

what is it? In a question it said which has the most lattice energy: K2O, MgO, KOH and NaCl. THe answer was MgO and i dont know why.

[airkyd]

ok lattice enthalpy is the over all energy change in the reaction: ok we ill take MgO for example,

 

natural states Mg (s) 02 (g).

 

before we can make Mgo , Mg and O2 must be atomised, then ionised for metal and some thing thats called electron affinity for non metal.

 

why is it done

 

Atomised - so they are in gaseous state and molcues like O2 ,Cl2 ect can be seperated (energy required)

 

Isonised/ Electron Affinity - to give the atoms charges. ( energy required for ionisation and 2nd, 3rd....ect electron affinities but energy given out for 1st electron affinity)

 

to turn the ions into MgO is call the lattcie enphalpy. ( energy is give off )

 

all of thsi requires energy , expect for the 1st electron affinity, when enery is given out the sum of all the energy put in and taken out is the other all energy in the system and therefore the negative value of the the energy required to turn.

Mg(2+) O(2-) into MgO.

 

sry im not the best teach or know much about this. only my second year of A levels.

[airkyd]

double post sry