According to the VSEPR theory, what is the shape of a molecule that has a central atom bound to three other atoms with no lone pairs of electrons?

1 Answer
Mar 31, 2016

Trigonal planar.

Explanation:

Three electron pairs surround a central atom, it doesn't matter whether they are bonding or not. VSEPR theory predicts that those electron pairs will be disposed in the geometry that minimizes electron pair repulsion. The result? A trigonal plane with angles of 120""^@ between the electron pairs. Examples include the boron halides, and unsaturated molecules such as ethylene.

Now, dichlorocarbene, :CX_2 also has 3 electron pairs around the central carbon, and the electron pairs, and the CX_2 bonds are likewise arranged in a trigonal plane. But we describe molecular geometry on the basis of atoms NOT lone pairs. This dichlorocarbene is predicted to be a bent molecule with Cl-C-Cl bond angles < 120""^@.