Let's do the NOCl Lewis structure.
On the periodic table, Nitrogen's in group
5, sometimes called 15: 5 valence electrons.
Oxygen, 6 valence electrons; and then Chlorine,
7 valence electrons; for a total of 18 valence
electrons.
Nitrogen is the least electronegative, that'll
go in the center.
We'll put an Oxygen on this side, and the
Chlorine over here.
We'll put two valence electrons between atoms
to form chemical bonds; we've used 2, 4.
Around the other atoms to get octets on those:
so we have 2, 4, 6, 8, 10, over here, 12,
14, 16, and then the last two go on the Nitrogen.
At this point, the Oxygen and the Chlorine
each have an octet; however, the Nitrogen
only has six valence electrons.
Let's move two valence electrons from the
Oxygen to form a double bond with the Nitrogen.
So the Oxygen still has eight valence electrons,
but now the Nitrogen has eight, as does the
Chlorine.
So we've used all 18 valence electrons and
each of the atoms has an octet, eight valence
electrons.
We did that by forming the double bond between
the Oxygen and the Nitrogen.
If you check the formal charges, you can see
that this is the best structure for NOCl,
and that the charges add up to zero.
This is Dr. B. with the Lewis structure for
NOCl, and thanks for watching.
