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Lattice enthalpy

Why is this, an example of enthalpy change of atomisation?
Na(s) ===> Na(g)

isnt it when a mole of gaseous ions is formed from an element in its standard state?

And also what is the diff between atomisation and bond dissociation.
e.g Cl2(g) ==> 2Cl(g) and 1/2Cl2(g)==>Cl

Both require the breakage of double bond?
And why is the enthalpy of atomisation = 1/2(enthalpy of dissociation)

Thanks.

(edited 10 years ago)

Reply 1

EierVonSatan

Gaseous atoms not ions - clue is in the name :p:

Reply 2

Big-Daddy

Original post by Zenarthra

And also what is the diff between atomisation and bond dissociation.
e.g Cl2(g) ==> 2Cl(g) and 1/2Cl2(g)==>Cl

None. But you've chosen a lucky case. There is no "bond dissociation enthalpy" of a large molecule, only of its individual bonds, but there is an "enthalpy of atomization" of that molecule (involving breaking all of its bonds, to produce gaseous phase atoms). The phase is also important - you can atomise anything into its constituent atoms in the gaseous phase, but bond dissociation enthalpies refer to gaseous phase bonds being broken to form gaseous phase product species.