Why substances can undergo sublimation and turn into gas?

[kfa]

Why is is that certain substances, (example: solid carbon dioxide) can undergo sublimation and turn into gas without undergoing liquid form when heated?

What is the general characteristics that enable certain substances to undergo sublimation?

Is it possible to have a substance that can undergo sublimation and melting process when heated?

 

[Claude Bile]

(You may be better served asking this in the chemistry forum.)

Sublimation can occur for just about any substance under the right conditions (for example, water can undergo sublimation when the pressure is less than that at the triple-point). In other words, I think you will find that the conditions (temperature and pressure) rather than the substance itself is more critical in determining whether sublimation occurs or not.

The next logical question is therefore "why do some substances more readily undergo sublimation at room temperature and pressure than others?". That is a question for the chemists.

Claude.