Ionic bonding

Sodium chloride

Metal combine with non metals to form giant ionic lattices

Ionic compounds form when the atoms of a metal combine with the atoms of a non - metal

Metal atoms lose electrons and therefore have an empty outer electron shell 

Non-metal atoms gain electrons and achieve a full outer electron shell  A full ( or empty) shell is a  stable arrangement.

Thus metal ions are positively charged and non-metal ions are negatively charged.

Remember: The total charge of an ionic compound is always zero.

With sodium chloride:

  • ​the Chloride ion formed carries a 1- charge.
  • The sodium ion carries a 1+ charge .
  • The ions thus combine together in a ratio of 1 : 1
  • and the formula is therefore NaCl: 

Students will be assessed on their ability to:

1.28 describe the formation of ions by the gain or loss of electrons
1.29 understand oxidation as the loss of electrons and reduction as the gain of electrons
1.30 recall the charges of common ions in this specification
1.31 deduce the charge of an ion from the electronic configuration of the atom from which the ion is formed
1.32 explain, using dot and cross diagrams, the formation of ionic compounds by electron transfer, limited to combinations of elements from Groups 1, 2, 3 and 5, 6, 7
1.33 understand ionic bonding as a strong electrostatic attraction between oppositely charged ions
1.34 understand that ionic compounds have high melting and boiling points because of strong electrostatic forces between oppositely charged ions
1.35 understand the relationship between ionic charge and the melting point and boiling point of an ionic compound
1.36 describe an ionic crystal as a giant three-dimensional lattice structure held together by the attraction between oppositely charged ions
1.37 draw a diagram to represent the positions of the ions in a crystal of 
sodium chloride 

Electrons are transferred..

The empirical formula of sodium chloride is NaCl

Dot and cross diagrams can be used to account for the electrons.  

Electrons are transferred from the metal atoms to the non metal atoms

In this way all the atoms achieve a full outer shell of electrons (Noble Gas configuration).

Magnesium Chloride

Monatomic ions

Monatomic ions. This pattern of charges extends down the groups shown

Polyatomic ions  

A neat trick..

A simple way to work out the formula of an ionic compound.

You can use this to balance the charges and work out the formula of any combination of positive and negative ions.