Image Ammonia molecule

TLF ID R6848

This is a colour image of a model of a molecule of ammonia, NH₃. In this model, atoms are represented by coloured spheres held together by grey rods, representing covalent bonds. The ammonia molecule consists of one nitrogen atom (the blue sphere) and three hydrogen atoms (the grey-white spheres).



Educational details

Educational value
  • Ammonia is a toxic, colourless gas with a characteristic pungent odour. It irritates the eyes and the mucous membranes of the nose. Many household cleaners contain ammonia dissolved in water. Although ammonia occurs naturally, large quantities are made synthetically to be used in fertiliser production.
  • The ammonia molecule has a pyramidal shape. The hydrogen atoms form the base of the pyramid and the nitrogen atom is the apex. The angle between the bonds is about 107 degrees.
  • The atoms in the ammonia molecule are connected by single covalent bonds. A covalent bond is formed when atoms share electrons. A single covalent has two shared electrons, one contributed by each atom. Because the nitrogen 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 electrons in these bonds are not shared equally; they are attracted more strongly to the nitrogen. This, combined with the pyramidal shape, results in the ammonia molecule having an electric dipole, and consequently ammonia molecules are strongly attracted to each other. This unusually strong attraction is termed ‘hydrogen bonding’. The hydrogen bonding in ammonia is weaker than it is in water.
  • 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.
Year level

7; 8; 9; 10; 11; 12

Learning area
  • science
Strand
  • Science/Science understanding

    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/
    Access profile
    • Device independence
    • Hearing independence
    Learning resource type
    • Image
    Browsers
    • Microsoft Internet Explorer - minimum version: 8.0 (MS-Windows) - maximum version: 9.0 (MS-Windows)
    • Firefox - minimum version: (MS-Windows)
    • Safari - minimum version: 5.1 (MacOS)
    Operating systems
    • MacOS - minimum version: 10.6
    • MS-Windows - minimum version: XP - maximum version: 7
    Rights
    • © Education Services Australia Ltd, 2013, except where indicated under Acknowledgements.