Bond Dissociation Enthalpy and Bond Length

Predict how the bond dissociation enthalpy and bond length will change if an electron is removed from Li2(g) molecule to form the Li2+ (g) ion.


One electron will be removed from the bonding pair right? So the electron left (not the 1s2 electrons) will be more strongly attracted to the side with less shielding and as a result (like difference in electronegativity maybe?), the bond length will increase. From this, I can say the bond dissociation enthalpy will decrease.

I know there's some wrong Chemistry in what I say, but is it a potential explanation, at least?

There is some funny old chemistry in the question...

I have never heard of a lithium molecule!

EDIT: Well here it is! http://en.wikipedia.org/wiki/Dilithium

So removal of an electron would have to be from the bonding electrons as there are no other valence electrons, so your logic is OK (except for the bit about more or less shielding - the atoms are both the same)

Many thanks for your response here.

I still didn't quite understand why the bond length increases.


Posted from TSR Mobile

The length and strength of a bond depends on the 'pull' exerted by the electrons in the bond and the two nuclei to which they are attracted. If there is less electron density in the bond it will be weaker and the bond longer.

The Q is more or less taken from last year's C3L6 exam.

Dilithium. Good old Star Trek.