Step method to draw lewis structure for XeF4( This molecules is an example of expanded octet)
Step 1: Find valence e- for all atoms. Add them together.
Step2: Find octet e- for each atom and add them together.
Bromine gets 12 electrons in order to make 5 bonds with surrounding atoms.
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.
36-8= 28e-=14 lone pairs
Use information from step 4 and 5 to draw the lewis structure.
Lewis dot structure of XeF4
Alternatively a dot method can be used to draw the lewis structure.
Calculate the total valence electrons in the molecule.
Put xenon in the center and four fluorine atoms on the sides.
Put a pair of electrons connecting the side atom with central atom.Put remaining electrons on the side atoms.Make sure each side atom get 8 electrons to get octet state.