• Covalent forms between pairs of non-metal atoms
  • Non-metal atoms need to receive electrons to fill the spaces in their outer shell
  • The atoms share some of their outer electrons so that each atom has a stable noble gas arrangement

    Structure of Covalent Bonds

    Atoms with covalent bonds are held together through electrostatic attraction between the nuclei and the shared electrons

    e.g. In a hydrogen molecule (H2), the two protons are held together by the pair of electrons.

    Forming Covalent Molecules

  • a group of covalently bonded atoms is called a molecule
  • in the example of Chlorine (Cl), which exists as a gas and therefore is a molecule Cl2
  • Chlorine has 8 electrons (in the orbitals [Ne] 2s2 2p5), the 2 atoms share one pair of electrons and therefore produces a stable noble gas.
  • The molecule has no charge as there are no electrons have been transferred from one atom too the other
  • Double Covalent Bonds

  • In a double bond, 4 electrons are shared
  • Double covalent bonds are presented as: =
  • They are present in alkenes and molecules such as O(O=O)
  • Properties of Covalent Bonds

  • Low melting points (the intermolecular covalent bond although strong, the intramolecular forces are weak)
  • Poor conductors of electricity (as each molecule has no overall charge)
  • Co-ordinate (dative) Bonding

  • A standard covalent bond is the sharing of a pair of electrons. Usually, one electrons comes from one atom, and one from the other
  • In co-ordinate bonding, the electron pair is provided by only the one atom
  • The atom that accepts the electron pair is the atom which has an incomplete outer main level of electrons. (or electron deficient)
  • The atom that is donating the electrons has a pair of electrons that is not being used in the bonds, called a lone pair
  • Co-ordinate bonds are represented as an arrow, where the arrow points towards the atom which is accepting the electron pair.
  • A Co-ordinate bond is equal in strength and bond length to a regular covalent bond