If a molecule possess 4 bonds and 2 lone pairs the Structure it can adopt is A. Octahedral B. See-saw C. Square planer D. Square pyramidal
The correct answer and explanation is:
Correct Answer: C. Square planar
When determining the molecular structure of a molecule based on the number of bonding and lone pairs, we use the Valence Shell Electron Pair Repulsion (VSEPR) theory. This theory helps predict the geometry of a molecule by considering how electron pairs repel each other.
In the given case, the molecule has 4 bonds and 2 lone pairs, which means there are 6 regions of electron density around the central atom. These 6 regions (4 bonding pairs + 2 lone pairs) correspond to an electron geometry of octahedral. This is because 6 electron regions are arranged around a central atom in an octahedral shape to minimize repulsion.
However, VSEPR theory distinguishes between electron geometry and molecular geometry. While the electron geometry is octahedral due to six electron regions, the molecular geometry depends only on the position of atoms, not the lone pairs.
When two of the positions in the octahedral arrangement are occupied by lone pairs and the other four by bonding atoms, the atoms arrange themselves in a square planar geometry. The lone pairs take up positions opposite each other (usually the axial positions) to reduce electron pair repulsion, leaving the four bonded atoms in a square plane.
This kind of structure is common in certain metal complexes, such as [PtCl₄]²⁻, where platinum is the central atom surrounded by four chlorine atoms and two lone pairs.
Therefore, a molecule with 4 bonds and 2 lone pairs will have a square planar molecular geometry due to the arrangement of atoms around a central atom that minimizes repulsion among all electron regions.
So, the correct answer is C. Square planar.