Ions & Ionic Bonding

The Formation of Ions

Ions are formed by the addition of electrons to, or the removal of electrons from, neutral atoms or molecules or other ions; by combination of ions with other particles; or by rupture of a covalent bond between two atoms.

Ions

An ion is an electrically charged atom or group of atoms formed by the loss or gain of electrons

This loss or gain of electrons takes place to gain a full outer shell of electrons

The electronic structure of an ion will be the same as that of a noble gas – such as helium, neon and argon

Ionisation of metals and non-metals

Metals: all metals lose electrons to other atoms to become positively charged ions

Non-metals: all non-metals gain electrons from other atoms to become negatively charged ions

Electrostatic attraction

The positive and negative charges are held together by the strong electrostatic forces of attraction between opposite charges.

This is what holds ionic compounds together

The Formation of Ionic Bonds, Groups I to VII

Example:  Sodium Chloride, NaCl

Sodium is a group 1 metal so will lose one outer electron to another atom to gain a full outer shell of electrons.

A positive sodium ion with the charge +1 is formed.

Chlorine is a group 7 non-metal so will need to gain an electron to have a full outer shell of electrons.

One electron will be transferred from the outer shell of the sodium atom to the outer shell of the chlorine atom.

A chlorine atom will gain an electron to form a negatively charged chloride ion with a charge of -1.

Formula of ionic compound:    NaCl

Ionic Bonds & Lattice Structure

Ionic Bonds between Metallic & Non-Metallic Elements

Example:  Magnesium Oxide, MgO

Magnesium is a group 2 metal so will lose two outer electrons to another atom to have a full outer shell of electrons

A positive ion with the charge +2 is formed

Oxygen is a group 6 non-metal so will need to gain two electrons to have a full outer shell of electrons

Two electrons will be transferred from the outer shell of the magnesium atom to the outer shell of the oxygen atom

Oxygen atom will gain two electrons to form a negative ion with charge -2

Formula of ionic compound:    MgO

The Lattice Structure of Ionic Compounds

Lattice structure

Lattice structure refers to the arrangement of the atoms of a substance in 3D space

In lattice structures, the atoms are arranged in an ordered and repeating fashion

The lattices formed by ionic compounds consist of a regular arrangement of alternating positive and negative ions