Image Phosphine molecule

TLF ID R6852

This is a colour image of a model of a molecule of phosphine, PH₃. In this model, atoms are represented by coloured spheres held together by grey rods, representing covalent bonds. The phosphine molecule consists of one phosphorus atom (the orange sphere) and three hydrogen atoms (the grey-white spheres).



Educational details

Educational value
  • Phosphine is a very toxic, colourless, odourless gas that does not occur naturally. It is widely used as a fumigant to kill insects in stored grain.
  • The atoms in the phosphine 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 the phosphorus atom is able to contribute three electrons, it is able to participate in three covalent bonds, whereas each hydrogen atom has only one electron to share and so can form only one bond.
  • The phosphine molecule has a pyramidal shape. The hydrogen atoms form the base of the pyramid and the phosphorus atom is the apex. It has a similar shape to the ammonia molecule, NH₃, reflecting the fact that nitrogen and phosphorus belong to the same group of the periodic table. In phosphine the bond angles are about 93 degrees, compared to 107 degrees in ammonia.
  • 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.

Other details

Contributors
  • Publisher
  • Date of contribution: 20 Sep 2013
  • Organisation: Education Services Australia
  • Address: Melbourne VIC 3000 Australia
  • URL: http://www.esa.edu.au/
  • Copyright holder
  • Organisation: Education Services Australia
  • Address: Melbourne VIC 3000 Australia
  • URL: http://www.esa.edu.au/
  • Remarks: Copyright Education Services Australia
  • Author
  • Date of contribution: 2006
  • Organisation: Education Services Australia
  • Address: Melbourne VIC 3000 Australia
  • URL: http://www.esa.edu.au/
  • Remarks: creator
  • Content provider
  • Organisation: Education Services Australia
  • Address: Melbourne VIC 3000 Australia
  • URL: http://www.esa.edu.au/
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Learning resource type
  • Image
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Rights
  • © Education Services Australia Ltd, 2013, except where indicated under Acknowledgements.