H2S has a very similar structure as H2O (see the lewis dot structure for H2O and the polar/nonpolar explanation at the linked addresses). However, due to the larger size of the sulfur atom compared to oxygen, the bond angle (i.e. the smaller angle between the two hydrogen atoms) is only 92˚ compared to 107.5˚ for H2O. Sulfur contains many more electrons which ultimately due to electron-electron repulsion require a lot more space. Nevertheless the decreased electronegativity of sulfur when compared to hydrogen (2.58 vs. 2.20, respectively) means that the molecule is much less polar overall when compared to H2O. This means that it has a much lower melting and boiling point at -82˚C and -60˚C, respectively. Like SO2 the presence of sulfur means that this molecule has a pungent odor in gaseous form although it is colorless.
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H2S Ball and Stick Diagram. Created with MolView. |