How do I know why the material Isobutane Has a low boiling point of Butane?
I know Isobutane is an Isomer of Butane.

Thanks.

Think about it for a while. What is the shape of the isobutane molecule?

You can compare isobutane and butane as a sphere and a stick respectively. Which one has a larger surface of contact with the similar adjacent molecules?

When spheres touch, do they touch over a large surface area? When sticks touch, do they touch over a large surface area?

And the larger the surface area of contact, the stronger the molecules can hold on to each other.

Can you now say which one has the higher boiling point?

Because for Isobutane has a smaller surface area.

When the surface area of Molecules is more Large the contact Between molecules is much more often and this Affects on the Gravity between them and make the boiling point to be more high. Yes?

Thnaks

Yes, but it's not gravity. The mass of the two molecules are too weak for that. These forces are often referred to as 'Van der Waal's' forces of attraction, or more specifically, induped dipole interactions.

:)