Question

The shape of a molecule is trigonal planar. How many electron domains around the central atom does this molecule most likely have?

Answer 1

There are three electron domains around the central atom. In a trigonal planar geometry, the central atoms is bonded to three other atoms or groups.

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Answer 2

Answer is: three electron domains around the central atom.

For example, molecule of benzene is trigonal (or triangular) planar.

VSEPR theory (The Valence Shell Electron Pair Repulsion Theory) uses the AXE notation (m and n are integers, m + n = number of regions of electron density).  

For benzene molecule (C₆H₆):  

m = 3; the number of atoms bonded to the central atom.  

n = 0; the number of lone pairs on the central atom.