Chemical Bonding - Covalent Non-Metals: Lewis Structure - Polyatomic Ions

Question 1

steps for drawing lewis structures

Answer 1

• least electronegative atom is in center
• hydrogen cannot be central atom
• determine shared electrons and number of bonds (shared=need-available, S=N-A)
• positive charge subtract electron from A
• negative charge add electron to A
• arrange remainder of electrons to fill octets

Question 2

PO_4^3-

Answer 2

• phosphorus has 5e- needs 8
• oxygens have 6e- x 4 = 24 needs 8 x 4 = 32
• S = N - A
• S = 40 - 32
• S = 8/2 = 4 bonds