Solved Examples on Lewis Dot Structure

Example: Draw the electron Lewis structure of water.

Solution:

• The chemical formula of water is H₂O.
• Valence electrons: In water, hydrogen (H) has 1 valence electron and oxygen (O) has 6 valence electrons, for a total of 8 valence electrons.
• Arrange the atoms: Place the oxygen atom in the centre and the two hydrogen atoms surrounding it.
• Create bonds: Using 2 valence electrons, form a single bond between each hydrogen and oxygen atom.
• Complete the octets: To complete the octets, add 6 electrons to the oxygen atom. These electrons can be arranged as 2 pairs of non-bonding electrons.
• Draw the structure: Represent the bonds with lines, and the non-bonding electrons with dots. The final Lewis structure for water would look like

 

Example 3: Draw the electron Lewis structure of CH₂O.

Solution:

• The chemical formula is CH₂O.
• Valence electrons: In CH₂O, hydrogen (H) has 1 valence electron, carbon (C) has 4 valence electrons and oxygen (O) has 6 valence electrons, for a total of 12 valence electrons.
• Arrange the atoms: Place the carbon atom in the centre and the two hydrogen and oxygen atoms surrounding it.
• Create bonds: Using 2 valence electrons of hydrogen, form a single bond between each hydrogen and carbon atom and using 2 valence electrons of oxygen, form a double bond between oxygen and a carbon atom.
• Complete the octets: To complete the octets, add 6 electrons to the oxygen atom. These electrons can be arranged as 2 pairs of non-bonding electrons of carbon. To complete the octets, add 6 electrons to the carbon atom after adding oxygen. These electrons can be arranged as 2 pairs of non-bonding electrons of hydrogen. 
• Draw the structure: Represent the bonds with lines, and the non-bonding electrons with dots. The final Lewis structure for water would look like this.

 

Example 3: Draw the electron Lewis structure of the carbonate ion.

Solution: 

• The chemical formula is CO₃^2-.
• Valence electrons: In CO₃^2-, carbon (C) has 4 valence electrons and 1 oxygen (O) has 6 valence electrons, and 2 oxygen has 2 valence electrons because they got 2 extra elements for a total of 24 valence electrons.
• Arrange the atoms: Place the carbon atom in the centre and the three oxygen atoms surrounding it.
• Create bonds: Using 2 valence electrons of negatively charged oxygen, form a single bond between each oxygen and carbon atom and using 2 valence electrons of oxygen, form a double bond between oxygen and a carbon atom.
• Complete the octets: To complete the octets, add 6 electrons to the oxygen atom. These electrons can be arranged as 2 pairs of non-bonding electrons of carbon. To complete the octets, add 6 electrons to the carbon atom after adding oxygen. These electrons can be arranged as 2 pairs of non-bonding electrons of negatively charged oxygen.. 
• Draw the structure: Represent the bonds with lines, and the non-bonding electrons with dots. The final Lewis structure for water would look like this.

 

Read, More

• Discovery of Electrons
• Proton
• Valence Electrons

Lewis Electron dot Structure is a type of representation of valence electrons of atoms and molecules and compounds with their bond structure. Atoms are the tiny particles of an element that are responsible for chemical reactions whereas, molecules are groups of atoms that are chemically bonded together. In this article, we will learn about, Lewis Electron Dot Structures in detail.