What are Lewis Symbols?

Lewis Symbols are used for representing electrons in the highest energy level of an atom. For example – The sodium atom has one electron in its highest energy level so its Lewis symbol is Na•, dot around Sodium Atomic Symbol Na representing a single electron.

Let’s now see how to draw Lewis Symbols.

How to draw Lewis Symbols?

In order to draw Lewis Symbol of any atom or molecule, you need to know what’s its electronic configuration? So as to find number of electrons in the highest energy shell. So follow below steps for drawing lewis symbol of an atom.

  1. Write Electronic Configuration of the atom
  2. Find shell which have highest energy, usually outermost shell
  3. Take symbol of atom and then put as many dots around it as there are electrons in highest energy shell

That’s it, this is how to draw Lewis Symbol of an atom.

For example – Let’s draw the lewis symbol of Carbon.
Electronic configuration of carbon is [He] 2s2 2p2. So Carbon atom have four electrons in its outermost shell(2). That’s why lewis symbol of Carbon will be carbon atomic symbol C surrounded by four dots.

Lewis Symbol of Carbon Atom, Carbon atomic symbol C surrounded by 4 dots which represents four electrons in its outermost shell

Why Lewis Symbols are important?

  • Lewis Symbols can be useful for understanding how an atom will react with other atoms
  • Lewis Symbols can be used for making structures of molecules which are also known as Lewis Structures
  • Lewis Symbols can be used for describing chemical reactions using Chemical Equations

Some examples of Lewis Symbol

Let’s draw lewis symbols of Chlorine, Aluminium and Calcium atoms. Firstly we need to write their electronic configurations.

AtomElectronic ConfigurationNumber of electrons in Outermost Shell
Chlorine[Ne] 3s2 3p57
Aluminium[Ne] 3s2 3p13
Calcium[Ar] 4s22

Lewis Symbol of Chlorine

Chlorine have electronic configuration [Ne] 3s2 3p5, so it have 7 valence electrons. So for drawing lewis symbol of Chlorine, just place 7 dots around the atomic symbol of Chlorine Cl.

Lewis Symbol of Chlorine showing chlorine atom surrounded by 7 dots each representing one electron in outermost shell of chlorine atom

Lewis Symbol of Aluminium

Aluminium have electronic configuration [Ne] 3s2 3p1, so it have 3 valence electrons. So for drawing lewis symbol of Aluminium, just place 3 dots around the atomic symbol of Aluminium Al.

Lewis Symbol of Aluminium showing aluminium atom surrounded by 3 dots each representing one electron in outermost shell of aluminium atom

Lewis Symbol of Calcium

Calcium have electronic configuration [Ar] 4s2, so it have 2 valence electrons. So for drawing lewis symbol of Calcium, just place 2 dots around the atomic symbol of Calcium Ca.

Lewis Symbol of Calcium showing calcium atom surrounded by 2 dots each representing one electron in outermost shell of calcium atom

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