[azmanr]

I don't understand this problem.

In solid I2 (iodine), is the distance between the two I nuclei of one I2 molecule longer or shorter than the distance between two I nuclei of adjacent I2 molecules?

[Dan]

Ok, if I label the I atoms it is easier to see, here are two I₂ molecules next to each other:

I_a-I_b  I_b-I_a

The question asks about the difference in lengths I_a to I_b compared to I_b to I_b.

[MrTeo]

Remember how bond energy is connected to bond lenght: what's the stronger bond there?

[azmanr]

Oh i think i kinda got it. Would the distance between the nuclei be shorter than the distance between the two molecules because I₂ are covalently bonded? Is that the right explanation and are there more pieces to it?ß

[MrTeo]

Oh i think i kinda got it. Would the distance between the nuclei be shorter than the distance between the two molecules because I₂ are covalently bonded? Is that the right explanation and are there more pieces to it?

Seems ok to me

[azmanr]

But it is also solid iodine. The distance between two iodine molecules would be close

[MrTeo]

Remember that solid iodine, being I₂ apolar, is kept together only by London forces (in fact it sublimates at low temperatures), so, compared with a covalent bond, the intermolecular forces are much more weaker and the distances between two I₂ longer.