Properties:

Thiols make extremely weak hydrogen bonds - much weaker as compared to alcohols - and so thiols have boiling points that are identical to comparable thioethers and that are lower than comparable alcohols. For instance, ethanethiol boils at 37?C while ethanol boils at 78?C. Low molecular weight thiols are notorious for comprising disagreeable aromas.

Reactivity

Thiols are the sulfur that is equivalent of alcohols (RSH). The sulfur atom is much larger and much more polarizable than oxygen that means that sulfur compounds like a whole are more powerful nucleophiles as compared to the corresponding oxygen compounds. Thiolate ions (for example CH₃CH₂ S^-) are stronger nucleophiles and weaker bases than subsequent alkoxides (CH₃CH₂O^-). On the other hand, thiols are stronger acids than corresponding alcohols.

The relative size variation between sulfur and oxygen as well means that bonding orbitals of sulfur are more diffuse than bonding orbitals of oxygen. This results in a poorer bonding interaction among the sulfur and hydrogen, than among oxygen and hydrogen. The result of it is that the S-H bond of thiols is weaker than the O-H bond of alcohols (80 kcal mol^-1  vs. 100 kcal mol^-1). In turn this means that the S-H bond of thiols is much more prone to oxidation than the O-H bond of alcohols.