Question

1. predict the molecular shape of cos (1 point) *

linear
bent
trigonal planar
trigonal pyramidal
tetrahedral

1. predict the molecular shape of ph3 (1 point) *

linear
bent
trigonal planar
trigonal pyramidal
tetrahedral

Explanation:

Question 14 (COS Molecular Shape)

Step1: Determine Lewis Structure

COS has a structure similar to CO₂ but with a sulfur. Carbon is central, double - bonded to O and S. The Lewis structure is \(O = C = S\).

Step2: Calculate Electron Domains

The central C has 2 double bonds (each double bond is 1 electron domain for shape prediction, as we consider bonding groups). So there are 2 electron domains (both bonding, no lone pairs on C).

Step3: Determine Molecular Shape

For a central atom with 2 bonding domains and 0 lone pairs, the molecular shape is linear (based on VSEPR theory: electron domain geometry and molecular shape are linear for 2 bonding domains with no lone pairs).

Step1: Determine Lewis Structure

Phosphorus is central, bonded to 3 H atoms. Phosphorus has 5 valence electrons, 3 are used in bonding with H, so there is 1 lone pair on P. The Lewis structure is \(H_3P\) with a lone pair on P.

Step2: Calculate Electron Domains

The central P has 3 bonding domains (with H) and 1 lone pair, so total electron domains = 4.

Step3: Determine Molecular Shape

The electron domain geometry is tetrahedral, but the molecular shape (considering only bonding groups) is trigonal pyramidal (because of 1 lone pair and 3 bonding groups; the lone pair repels the bonding pairs, giving a trigonal pyramidal shape, similar to NH₃).

Answer:

A. Linear

Question 15 (PH₃ Molecular Shape)