Covalent Bonding 6

Molecules of Compounds

• molecules made from 2 or more different atoms linked together make up compounds

• many elements are made up of molecules that contain 2 or more identical atoms linked together

Covalent Bond

• the attractive force formed by the sharing of electrons

• between nonmetallic elements of similar electronegativity

• formed by sharing electron pairs so that they can acquire the noble gas electronic configuration

• stable non-ionising particles → not conductors at any state

• bonds in all the polyatomic ions and diatomic are all covalent bonds

Melting and Boiling Points

• low melting and boiling points

• bonds formed from sharing electrons amongst atoms within the molecule is strong and will not break easily

• intermolecular attraction is weak → molecules are easily separated form each other

Softness and Malleability

• covalent molecules are soft and malleable (e.g. graphite)

  • explained by weak attraction among molecules → easy to separate 1 molecule from another

Solubility in Water

• large variation in solubility

• some are highly soluble in water (e.g. ethanol, glucose)

• some are insoluble (wax, oil)

• non-polar covalent molecules - insoluble in water, soluble in organic solvents

• polar covalent molecules - soluble in water

Electrical Conductivity

• non-conductor of electricity

  • pure covalent molecular substances do not have charges

• however, highly polar covalent molecular compounds (HCl) ionise completely in water

  • ∴aqueous solutions of these covalent compounds contains ions, resulting in conduction of electricity

Covalent Compounds

• covalent molecular compounds - covalent bonding between atoms

• non-polar covalent - when electrons are shared equally by contributing atoms

• polar covalent - when the electron cloud is distorted towards the more electronegative atom resulting in partial charges in the molecule