Question

molecule assigned axe geometry polarity
pn₂⁻ ax₂e v - shaped 120° polar
lewis structure
molecule assigned axe geometry polarity
clo₃⁻ ax₃e trigonal pyramidal ~109.5° polar
lewis structure
molecule assigned axe geometry polarity
h₂o ax₂e₂ bent - 109.5° polar
lewis structure

Explanation:

Step1: Determine Lewis structure for $PN_2^{-}$

The central - atom P has 5 valence electrons, each N has 5 valence electrons, and there is an extra electron due to the negative charge. Total valence electrons = 5 + 2×5+1 = 16. The Lewis structure has P as the central atom double - bonded to each N, with a lone pair on P.

Step2: Determine Lewis structure for $ClO_3^{-}$

Cl has 7 valence electrons, each O has 6 valence electrons, and there is an extra electron due to the negative charge. Total valence electrons = 7+3×6 + 1=26. The Lewis structure has Cl as the central atom single - bonded to three O atoms, with one O having a double - bond and a lone pair on Cl.

Step3: Determine Lewis structure for $H_2O$

O has 6 valence electrons and each H has 1 valence electron. Total valence electrons = 6+2×1 = 8. The Lewis structure has O as the central atom single - bonded to two H atoms, with two lone pairs on O.

Answer:

For $PN_2^{-}$:
Lewis structure: P is the central atom with double - bonds to two N atoms and a lone pair on P.
For $ClO_3^{-}$:
Lewis structure: Cl is the central atom single - bonded to three O atoms, with one O having a double - bond and a lone pair on Cl.
For $H_2O$:
Lewis structure: O is the central atom single - bonded to two H atoms, with two lone pairs on O.