Step 1: Find valence e- for all atoms. Add them together.
Step2: Find octet e- for each atom and add them together.
Step3: Gives you bonding e-. Subtract step 1 total from step 2
Step 4: Find number of bonds by diving the number in step 3 by 2(because each bond is made of 2 e-)
8e-/2= 4 bond pairs
Step 5: Find the number of nonbonding (lone pairs) e-. Subtract step 3 number from step 1.
10-8= 2e-=1 lone pair
Use information from step 4 and 5 to draw the lewis structure.
Carbon goes in the centre.Make sure carbon and Nitrogen get 8 electrons to fulfil octet rule.
Lewis dot structure of HCN
Alternatively a dot method can be used to draw the lewis structure of BF3.
Calculate the total valence electrons in BF3 molecule.
Put carbon in the center and hydrogen and oxygen on the sides.
Put a pair of electrons connecting the side atom with central atom.Put remaining electrons on the side atoms.Move electrons fron oxyfgen so that both carbon and oxygens get octet state.