There’s always van der Waals’
Dedicated to the all A-level Chemists at St Edward’s*

(The teacher strums on his guitar through the first 3 phrases, then the lesson begins…)

"One day, there’s bound be a day that they’re gonna to test you out on forces;
By now, you should have learned how they work out from your different sources.
I don’t believe that anybody should be feeling scared about them now,

But here’s a little song as a reminder…"

"H-bonds are really pretty strong, about 30 kJ per mole.
Hydrogen is bonded to a F/O/N element in a real strong dipole,
H must be bonded to electronegativity of at least three.
That’s why its fluorine, oxygen or nitrogen,
And a lone pair’s vital for the bonding,
Sharing its electrons but now datively
With the delta +."

"But teacher,
What if they don’t have this feature?"
"Well underneath it all,
There’s always van der Waals’."

"Fluorine’s arriving on the scene diatomically that’s undisputed;
Generally, the electron density is randomly distributed."
"We don’t believe that helps us to explain the boiling trend as we go down."
"Let’s take a closer look there for a moment…
There’s temporary delta + and –,
Inducing these same charges in the neighbouring molecules."
"We can see it now!"

"It may be,
The weakest type of force but baby;
By larger iodine,
A stronger force is seen."

"With more shells,
Electrons they become less well held,
And temporarily,
They polarise more easily."

"When longer,
The forces between chains get stronger,
Whatever else befalls;"
"There’s always van der Waals’ !"

*For Lorna, Neil, Glenn, Natalie, Joe, Claire, Naomi, Leilani, Sara, Michael, Esteban, Jenny, Alex, Katie, Ben, Theresa and Adam.
 May the force be strong in this one…

C Downey, February 2001