What is the molecular geometry (shape) of S atom in SO42-
The correct answer and explanation is:
The molecular geometry of the sulfur (S) atom in the sulfate ion (SO₄²⁻) is tetrahedral.
In the sulfate ion (SO₄²⁻), sulfur is at the center, and it is bonded to four oxygen atoms. The sulfur atom has a formal charge of +6, while the oxygen atoms have a formal charge of -2 each, resulting in an overall charge of -2 on the ion. Sulfur’s electron configuration in this case is expanded, meaning it uses d-orbitals to accommodate more than the typical eight electrons in its valence shell.
The sulfate ion follows the principles of the valence shell electron repulsion (VSEPR) theory, which helps predict the shape of molecules and ions based on electron pairs around the central atom. In the case of SO₄²⁻, there are four bonding pairs of electrons and no lone pairs on the sulfur atom. These bonding pairs of electrons are arranged as far apart as possible to minimize electron pair repulsion.
The result is a tetrahedral molecular geometry where the four oxygen atoms are arranged at the corners of a tetrahedron, and the sulfur atom sits at the center. The bond angle between the oxygen atoms in this geometry is approximately 109.5 degrees. This shape is typical for molecules and ions where a central atom is surrounded by four bonding atoms and no lone pairs.
The sulfate ion’s structure and its symmetry make it a very stable and relatively non-reactive species in many chemical reactions. The tetrahedral geometry is also characteristic of other molecules and ions with similar bonding, such as methane (CH₄) or ammonium (NH₄⁺).