Key Concepts: Ionic Bonding

Ionic bonding involves the transfer of electrons from one atom to another. It occurs between a metal and a non-metal.
Atoms lose or gain electrons to achieve a stable electron configuration similar to that of noble gases. This is often referred to as the ‘octet rule’ – atoms strive to have eight electrons in their outer shell.
Metals, which have few electrons in their outer shell, will tend to lose these electrons. This will result in a positively charged ion, also known as a cation.
Non-metals, on the other hand, with a large number of electrons in their outer shell, will tend to gain electrons to complete their outer shell. This leads to the formation of a negatively charged ion, also known as an anion.
The strong electrostatic forces of attraction between the oppositely charged ions formed is what we call an ionic bond.
The resulting substance is known as an ionic compound. These compounds arrange themselves in a giant ionic lattice structure.
Ionic compounds have high melting and boiling points because of the strong attraction between the ions. They are generally solid at room temperature.
In a solid state, ionic compounds do not conduct electricity. However, when they are dissolved in water or melted, they become able to conduct electricity as the ions are free to move.
Examples of ionic compounds include common table salt (sodium chloride), calcium chloride, and potassium iodide.
It is important to note that while ionic bonding often results in a neutral compound, it does not always mean that one electron is transferred. Some elements may lose or gain more than one electron. For example, magnesium loses two electrons to form a 2+ ion, and oxygen gains two electrons to form a 2- ion.
Examining electron configuration and the periodic table can help predict what ions elements will form, which can then be used to predict the formula of the ionic compound.
The charge on the ion relates to the group on the periodic table. Group 1 elements form 1+ ions, Group 2 elements form 2+ ions, Group 6 elements form 2- ions, and Group 7 elements form 1- ions.
The properties of ionic compounds can be explained by the ionic bonding and structure, including the ability to form crystals, high melting and boiling points, and the ability to conduct electricity when dissolved or molten.