Image Hydrogen sulfide molecule

TLF ID R6845

This is a colour image of a model of a molecule of hydrogen sulfide, H₂S. In this model, atoms are represented by coloured spheres held together by grey rods, representing covalent bonds. The hydrogen sulfide molecule consists of one sulfur atom (the yellow sphere) and two hydrogen atoms (the grey-white spheres).

Educational details

Educational value
  • Hydrogen sulfide is the gas responsible for the foul odour of rotten eggs and is commonly known as ‘rotten-egg gas’ for this reason. It is often produced when bacteria break down organic materials in the absence of oxygen. It is also responsible for the so-called ‘sulfurous’ odour of volcanic gases. Hydrogen sulfide is flammable and extremely toxic. Its toxicity is heightened by the fact that although its odour is very noticeable at first, it quickly deadens the sense of smell, giving the impression that it is no longer present.
  • The atoms in the molecule are connected by single covalent bonds. A covalent bond is formed when atoms share electrons. A single covalent bond has two shared electrons, one contributed by each atom. Because a sulfur atom is able to contribute two electrons, it is able to participate in two covalent bonds, whereas each hydrogen atom has only one electron to share and so can form only one bond.
  • This molecule, H₂S, has a similar shape to the water molecule, H₂O, reflecting the fact that oxygen and sulfur belong to the same group of the periodic table. However, the angle between the bonds in H₂S is 92.2 degrees, compared with 104.5 degrees in H₂O. The trend continues in the hydrogen compounds of other members of this group, so that the larger the central atom, the smaller the bond angle.
  • The type of model shown here, called a ball-and-stick model, is one of several ways of modelling molecules. This type is useful because it clearly shows the geometry of the molecule and the order (single, double or triple) of the bonds. However, because 'sticks' are used to represent bonds, this type of model does not represent the actual shape of the molecule as well as 'space-filling' models do.

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  • Date of contribution: 20 Sep 2013
  • Organisation: Education Services Australia
  • Address: Melbourne VIC 3000 Australia
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  • Organisation: Education Services Australia
  • Address: Melbourne VIC 3000 Australia
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  • Remarks: Copyright Education Services Australia
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  • Date of contribution: 2006
  • Organisation: Education Services Australia
  • Address: Melbourne VIC 3000 Australia
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  • Remarks: creator
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  • © Education Services Australia Ltd, 2013, except where indicated under Acknowledgements.