Learning objectives

As shown below most non-metallic elements exist as molecules in which two or more of the atoms are linked by covalent bonds.
 
 Group 15Group 16Group 17
H2N2O2F2
 P4S8Cl2
   Br2
   I2

A covalent bond is a shared electron pair. 
Depending on the atoms involved, more than one electron pair may be shared by the bonded atoms.
 
Single bonds 
(one shared electron pair)
Double bonds
(two shared electron pairs)
Triple bonds
(three shared electron pairs)
 
This activity is concerned with the nature of covalent bonding between the atoms of the same element.  On completion of the activity you should be able to
 
  • to describe the potential energy changes that occur when nonbonded atoms with unpaired electrons approach one another
     
  • to draw the Lewis electron dot representation of an atom with is valence (outer-shell) electrons
     
  • to use the Lewis electron dot representation of an atom to predict the number and type of covalent bonds formed between those atoms in the elemental form