ArtsAutosBooksBusinessEducationEntertainmentFamilyFashionFoodGamesGenderHealthHolidaysHomeHubPagesPersonal FinancePetsPoliticsReligionSportsTechnologyTravel

Electron-Pair Repulsion Theory

Updated on December 30, 2012

What is it?

  • The Electron-Pair Repulsion Theory is basically a theory that states that the valence electron pairs surrounding an atom will mutually repel each other and thus determine the molecular geometry or shape of the molecule itself.
  • From this theory you can predict the shape of a molecule based on the extent of the electrostatic repulsion of the electron pairs.

How does it work?

Imagine trying to force the same poles of two magnets together, what would happen? They would repel each other! This is much the same for electrons, because they are negatively charged the electron pair in the outer shell of the central atom of a molecule will repel the other electron pairs in the other atoms of the molecule.

This repulsion will cause the electron pairs to move as far away from each other as possible, whilst keeping within the confines of the intermolecular bonds that are holding the molecule together.

The molecule will then form a 3-Dimensional shape because of this.

Below are the main shapes that molecules can form.

Linear Molecules

  • An example of a linear molecule (as seen in the picture to the right) is Beryllium Hydride (BeH2).
  • Linear molecules have 2 bonded pairs of electrons and no lone pairs.
  • The bonds will repel as far as possible and create a molecule with a bond angle of 180o.

Non-Linear Molecules

  • An example of a Non-Linear molecule is H2O (water).
  • Because there are 6 outermost electrons in an oxygen atom and only 1 outermost electron in each hydrogen atom, the H2O molecule will have 2 bonded pairs of electrons and 2 lone pairs of electrons.
  • The lone pairs will repel more than the bonded pairs of electrons and therefore repel the other bonded electron pairs further away from itself.
  • This repulsion creates a Non-Linear (or 'bent') shape with bond angles of 104o.

Trigonal Planar Shapes

  • An example of a molecule with a trigonal planar shape is Boron Triflouride (BF3).
  • Boron Triflouride has 3 bonded pairs of electrons and no lone pairs.
  • This molecule is very reactive and will accept lone pairs of electrons.
  • Because of the equal repulsion between the atoms, Boron Triflouride forms a Trigonal Planar shape with a bond angle of 120o.

Trigonol Bipyramidal Shape

  • An example of a molecule with a Trigonol Bipyramidal shape is Ammonia (NH3).
  • Ammonia has three bonding pairs and one lone pair of electrons on the central nitrogen atom.
  • The lone pair decreases the bond angle of the atom because it repels more than the bonded pairs.
  • This gives the Ammonia molecule a Trigonol Bipyramidal shape with a bond angle of 107o.

Tetrahedral Shape

  • Methane (CH4) is an example of a molecule with a tetrahedral shape.
  • There are 4 bonding pairs of electrons between the atoms and no lone pairs.
  • These pairs repel each other to the corners of a regular tetrahedron.
  • This creates the tetrahedral shape of the molecule, with a bond angle of 109.5o.

Octahedron Shape

  • An example of a molecule with an octahedron shape is Sulfur Hexaflouride (SF6).
  • It has 6 bonded pairs and no lone pairs.
  • All of the bonded pairs in Sulfur Hexaflouride repel equally.
  • The bond angles in an octahedron shaped moleculeare 90o.


    0 of 8192 characters used
    Post Comment

    No comments yet.


    This website uses cookies

    As a user in the EEA, your approval is needed on a few things. To provide a better website experience, uses cookies (and other similar technologies) and may collect, process, and share personal data. Please choose which areas of our service you consent to our doing so.

    For more information on managing or withdrawing consents and how we handle data, visit our Privacy Policy at:

    Show Details
    HubPages Device IDThis is used to identify particular browsers or devices when the access the service, and is used for security reasons.
    LoginThis is necessary to sign in to the HubPages Service.
    Google RecaptchaThis is used to prevent bots and spam. (Privacy Policy)
    AkismetThis is used to detect comment spam. (Privacy Policy)
    HubPages Google AnalyticsThis is used to provide data on traffic to our website, all personally identifyable data is anonymized. (Privacy Policy)
    HubPages Traffic PixelThis is used to collect data on traffic to articles and other pages on our site. Unless you are signed in to a HubPages account, all personally identifiable information is anonymized.
    Amazon Web ServicesThis is a cloud services platform that we used to host our service. (Privacy Policy)
    CloudflareThis is a cloud CDN service that we use to efficiently deliver files required for our service to operate such as javascript, cascading style sheets, images, and videos. (Privacy Policy)
    Google Hosted LibrariesJavascript software libraries such as jQuery are loaded at endpoints on the or domains, for performance and efficiency reasons. (Privacy Policy)
    Google Custom SearchThis is feature allows you to search the site. (Privacy Policy)
    Google MapsSome articles have Google Maps embedded in them. (Privacy Policy)
    Google ChartsThis is used to display charts and graphs on articles and the author center. (Privacy Policy)
    Google AdSense Host APIThis service allows you to sign up for or associate a Google AdSense account with HubPages, so that you can earn money from ads on your articles. No data is shared unless you engage with this feature. (Privacy Policy)
    Google YouTubeSome articles have YouTube videos embedded in them. (Privacy Policy)
    VimeoSome articles have Vimeo videos embedded in them. (Privacy Policy)
    PaypalThis is used for a registered author who enrolls in the HubPages Earnings program and requests to be paid via PayPal. No data is shared with Paypal unless you engage with this feature. (Privacy Policy)
    Facebook LoginYou can use this to streamline signing up for, or signing in to your Hubpages account. No data is shared with Facebook unless you engage with this feature. (Privacy Policy)
    MavenThis supports the Maven widget and search functionality. (Privacy Policy)
    Google AdSenseThis is an ad network. (Privacy Policy)
    Google DoubleClickGoogle provides ad serving technology and runs an ad network. (Privacy Policy)
    Index ExchangeThis is an ad network. (Privacy Policy)
    SovrnThis is an ad network. (Privacy Policy)
    Facebook AdsThis is an ad network. (Privacy Policy)
    Amazon Unified Ad MarketplaceThis is an ad network. (Privacy Policy)
    AppNexusThis is an ad network. (Privacy Policy)
    OpenxThis is an ad network. (Privacy Policy)
    Rubicon ProjectThis is an ad network. (Privacy Policy)
    TripleLiftThis is an ad network. (Privacy Policy)
    Say MediaWe partner with Say Media to deliver ad campaigns on our sites. (Privacy Policy)
    Remarketing PixelsWe may use remarketing pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to advertise the HubPages Service to people that have visited our sites.
    Conversion Tracking PixelsWe may use conversion tracking pixels from advertising networks such as Google AdWords, Bing Ads, and Facebook in order to identify when an advertisement has successfully resulted in the desired action, such as signing up for the HubPages Service or publishing an article on the HubPages Service.
    Author Google AnalyticsThis is used to provide traffic data and reports to the authors of articles on the HubPages Service. (Privacy Policy)
    ComscoreComScore is a media measurement and analytics company providing marketing data and analytics to enterprises, media and advertising agencies, and publishers. Non-consent will result in ComScore only processing obfuscated personal data. (Privacy Policy)
    Amazon Tracking PixelSome articles display amazon products as part of the Amazon Affiliate program, this pixel provides traffic statistics for those products (Privacy Policy)