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Learning about Ionic Bonding - Chemistry Revision

In order to gain full outershell atom looses, gains or share electron with another atom and takes part in chemical bonding. Chemical bonding is of three types-Ionic Bonding, Metallic Bonding and Covalent Bonding. Ionic bonding involves loosing and gaining electrons and it takes place between a metal and a non metal. Metallic bonding takes place within the metal and Covalent bonding takes place between non metals and it involves sharing of electrons. In this article we are focussing on Ionic bonding.


To study ionic bonding in detail we need to be clear about the definition of an ion. Whenever atoms gain or loose electrons, electrically charged particles are formed which can be positive or negative. They are called ions and have the same electronic structure as noble gasses. Metals form positive ions and non metals form negative ions.

Formation of Ions

Ions are electrically charged particles which are formed when atom gain or loose electrons. Metal and non metal atoms go in opposite direction when they ionise. Metals – loose electrons in their highest energy level and become positively charged ions.

Sodium( Na+)

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In the figure above we can see that sodium has an electronic configuration of 2,8,1. Sodium atom looses an electrons and got a noble gas configuration of 2,8 and formed a positive sodium ions.

Lithium (Li+)

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In the figure above Lithium atom also looses an electron and becomes positively charge lithium ions. 

Non metals on the other hand form ions by gaining an electron in their outermost shell gaining negative charge and attain a noble gas configuration. 


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In the figure above fluorine atom has gained an electron in its outermost shell and formed F- ion.

Ionic bonding

Ionic bonding is a bonding formed between a metal and a non metal. In ionic bonding, metal looses and electron and forms negatively charge ions and non metal gains an electron and form negatively charged ions. The strong electrostatic force of attraction between positive and negative charged ions results in ionic bonding. 
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Example – Sodium(metal ) + Chlorine(non-metal) = Sodium Chloride (ionic compound)

In this process the metal atoms become positive ions and the non metal atoms become negative ions. Between the positive and the negative ions there is a strong electrostatic force of attraction called ionic bond.

Group 1 and Group 7

The elements in group 1 are known as alkali metal. They form ionic bond with non – metals . Their ions have a single positive charge .
Example : Na+
The elements of group 7 are called halogens . They form ionic compound when they react with metals and their ions have a single negative charge .
Example : Cl-

Dot and cross diagrams

Dot and cross diagrams represent the gain and loose of electrons from two atoms in order to form an ionic bond.

a) Sodium Chloride

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Sodium ion have a positive charge by loosing one electron represented by red dot. Whereas chloride ion has a negative charge as it gained an electron from sodium to make the complete outer shell like noble gases.

b) Magnesium Oxide
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Here magnesium ion has 2 positive charges as it has lost two electrons to oxygen atom and oxygen atom has formed oxide ion by gaining two electrons. 

Constructing Formula Of Ionic Compounds

The formula can be worked out easily if the ions in it are known. For example: the compound formed from Na+ and SO42- will have 2 Na+ ions to every one SO42- so that the overall compound is neural. Hence the formula : Na2SO4. Symbols and number shows the atom in the compounds. For example : ZnCO3 has one zinc atom and one Carbon atom bonded with three oxygen atom.

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