Dot and cross diagrams of ionic bonding

An ionic bond is formed when electrons are transferred from a metal to a non-metal, forming an ionic compound. The compound is held together by the electrostatic attraction between the positively charged metal ions and negatively charged non-metal ions.

Dot and cross diagrams are often used to represent ionic bonding. For one ion electrons are shown as dots, and for the other ion as crosses. Typically only outer-shell electrons are shown, and charges are shown outside square brackets surrounding the ion.

The table below shows the dot and cross diagram of ssodium chloride, magnesium oxide, and calcium fluoride:

Compound	Ions	Formation of ions	Dot and cross diagram
Sodium chloride (NaCl)	Na⁺ and Cl^-	Na donates an electron to Cl.
Magnesium oxide (MgO)	Mg²⁺ and O^2-	Mg donates two electrons to O.
Calcium fluoride (CaF₂ )	Ca²⁺ and F^-	Ca donates two electrons to 2 F.

Activity:

1. Describe ionic bonding in terms of ions and electrons.

2. What is an ion?

3. Describe what has to happen to metals and non-metals to become ions.

4. Which group of elements has a full outer shell?

5. What occurs when a metal forms an ionic bond with a non-metal?

Click on the following link for Solutions: Solutions

References and Attributions

Question mark by Vectorink from Wikimedia commons, CCO 1.0

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