• A?covalent bond?is the sharing of two or more electrons between two atoms
  • The electrons can be shared equally forming a?nonpolar?covalent bond or unequally (where an atom can be more?electronegative?δ-) to form a?polar?covalent bond
• Generally each atom will form a certain number of covalent bonds due to the number of free electrons in the outer orbital e.g. H = 1 bond, C = 4 bonds
• Covalent bonds are very stable as high energies are required to break the bonds
• Multiple pairs of electrons can be shared forming?double?bonds (e.g. unsaturated fats C=C) or?triple?bonds

Different types of covalent bonds

• When two monomers are close enough that their outer orbitals overlap this results in their electrons being shared and a covalent bond forming. If more monomers are added then?polymerisation?occurs (and / or a macromolecule forms)

Condensation

• Also known as dehydration synthesis (‘to put together while losing water’)
• A?condensation reaction?occurs when?monomers?combine together by?covalent bonds?to form?polymers?(polymerisation) or macromolecules (lipids) and?water?is?removed

Written and symbolic illustrations of the removal of water to form a covalent bond between two or more monomers during a condensation reaction

Hydrolysis

• Hydrolysis means ‘lyse’ (to break) and ‘hydro’ (with water)
• In the hydrolysis of polymers,?covalent bonds?are?broken?when?water?is?added

Written and symbolic illustrations of the addition of water to break down covalent bond/s during a hydrolysis reaction

Covalent bonds in organic molecules table