Question

Oxygen and sulfur have similar chemical properties because both elements have six electrons in their outermost electron shells. Indeed, both oxygen and sulfur form molecules with two hydrogen atoms: water and hydrogen sulfide. Surprisingly, water is a liquid, yet hydrogen sulfide is a gas, even though sulfur is much larger and heavier than oxygen. Propose an explanation for this striking difference.

Answer 1

Because water is a liquid, we can conclude that it must have stronger intermolecular forces than the gaseos hydrogen sulfide.

This is true because water is held together in large part by hydrogen bonding, the extremely strong interactions between hydrogen and fluorine, oxygen or nitrogen. Hydrogen sulfide does not have hydrogen bonding so the intermolecular forces are much weaker.

Thus, hydrogen sulfide exists as a gas while water is a liquid.

Answer 2

Electro negativity and polarity of the bond in the both molecules

Step-by-step explanation:

Approaching the matter from an electro negativity perspective, oxygen is more electronegative than sulphur. This implies that the O-H bind is more polar than the S-H bond.

The high polarity of the O-H bond leads to a higher degree of hydrogen bonding in H2O than in H2S. This higher degree of hydrogen bonding in H2O leads to greater intermolecular association and the substance is a liquid. Hence H2O is liquid but H2S is a gas.