Covalent compounds

2.1.2 Ionic compounds

2.1.4 Macromolecules

Covalent compounds

  1. Bonding

    1. When atoms share pairs of electrons, they form covalent bonds, which are very strong

    2. Covalent bonds can be represented on a diagram in different ways:

      1. A Dot & Cross diagram shows the valence electrons on a circle with each pair of shared electrons as a dot & a cross in the overlap between the two circles
      2. A Lewis structure shows each pair of shared electrons as a line between the atoms, and lone pairs as dots
    3. Compounds formed by non-metals consist of molecules in which the atoms are held together by covalent bonds

  2. Structure

    1. Some covalently-bonded substances consist of simple molecules
    2. Others have giant covalent structures called macromolecules

  3. Properties

    1. Covalent compounds that consist of simple molecules have relatively low melting & boiling points since they involve overcoming the intermolecular forces, van der Waals forces which are relatively easy to overcome, rather than the covalent bonds
    2. They do not conduct electricity because the molecules do not have an overall electrical charge