# Ionic bonding

When a reacts with a , the metal transfers to the non-metal.

The metal has lost electrons and forms positive , also called . The non-metal has gained electrons and so forms negative ions, also called . The ions have opposite , so are strongly attracted to each other. These attractions make .

An explanation of ionic bonding

## Dot and cross diagrams

A dot and cross diagram can model the transfer of electrons from metal to non-metal atoms. The electrons in one atom are shown as dots, and the electrons in the other atom are shown as crosses. For example, when sodium reacts with chlorine, electrons transfer from sodium atoms to chlorine atoms.

The outer electron from a sodium atom transfers to the outer shell of a chlorine atom

## Drawing dot and cross diagrams

When drawing a dot and cross diagram, it is usual to show:

• the atoms that are going to react, with their electrons as dots or crosses (it is usual for only the outer shell of electrons to be shown)
• arrows showing the outer electrons from the metal atoms being transferred to the non-metal atoms
• a separate diagram, showing the ions formed - the ions should have a full outer shell of electrons
• the charge of the ions formed

## Modelling ionic bonding

The slideshow shows dot and cross diagrams for the ions in sodium chloride, magnesium oxide and calcium chloride.