Ionic Bonds: Dot & Cross Diagrams (Edexcel IGCSE Chemistry: Double Science)

Deducing Dot & Cross Diagrams for Ionic Compounds

• 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

Sodium chloride ionic bonding

Magnesium Oxide Dot & Cross Diagram

• 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

Diagram showing the dot-and-cross diagram of magnesium oxide