Question

question 3 (1 point)
what is the electron geometry and molecular geometry for nh₃?
a) electron geometry: trigonal planar
molecular geometry: trigonal pyramidal
b) electron geometry: tetrahedral
molecular geometry: tetrahedral
c) electron geometry: tetrahedral
molecular geometry: trigonal planar
d) electron geometry: tetrahedral
molecular geometry: trigonal pyramidal

Explanation:

• Electron geometry:
• For \(NH_3\), the central atom is \(N\). The number of valence electrons of \(N\) is \(5\). Each \(H\) atom contributes \(1\) electron. Using the formula for the number of electron - pairs around the central atom \(=\frac{V + M - C + A}{2}\) (where \(V\) is the valence electrons of the central atom, \(M\) is the number of monovalent atoms, \(C\) is the charge for cations, \(A\) is the charge for anions). Here, \(V = 5\), \(M=3\), \(C = 0\), \(A = 0\). The number of electron - pairs \(=\frac{5 + 3}{2}=4\). According to VSEPR (Valence - Shell Electron - Pair Repulsion) theory, when the number of electron - pairs is \(4\), the electron geometry is tetrahedral.
• Molecular geometry:
• In \(NH_3\), there are \(3\) bonding pairs and \(1\) lone pair. The lone pair - bond pair repulsion is greater than bond pair - bond pair repulsion. The molecular geometry (which considers only the arrangement of atoms) is trigonal pyramidal.

Answer:

D. Electron geometry: tetrahedral, Molecular geometry: trigonal pyramidal