Question

Which has a trigonal planar molecular geometry?

a. Nitrate
b. Ammonium
c. Sulfate
d. no right answer

Answer 1

Nitrate has a planar molecular geometry

Step-by-step explanation:

Number of electron groups Geometry Formula

2 linear AX2

3 trigonal-planar AX3 or AX2E

4 tetrahedral AX4/AX3E/AX2E2

a) Nitrate = NO3-

⇒ AX3

⇒ bond angles = 120°

⇒ Coordination number = 3

⇒ Trigonal planar

b) ammonium = NH4+

Nitrogen atom is at the center and three Hydrogen atoms are at three vertices. The lone pair on N points to the fourth vertice.

⇒AX4

⇒ bond angles = 190.5°

⇒Coordination number = 4

⇒Tetrahedral

c) Sulfate= SO42-

The central S -atom has four electron domains. It has no lone pairs, so the electron geometry and the molecular geometry are tetrahedral.

⇒AX4

⇒ bond angles = 190.5°

⇒Coordination number = 4

⇒Tetrahedral

Option A, nitrate is the correct answer.