Question

sulfate ion so₄²⁻ will have which of the following? (hint: you will have to try out lewis structure drawing before you can come up with correct answer; and dont forget it has -2 charge

1. tetrahedral for both electron and molecular geometries
2. tetrahedral electron geometry and trigonal pyramid molecular geometry
3. trigonal pyramid for both electron and molecular geometry
4. tetrahedral for electron geometry and trigonal planar for molecular geometry

Explanation:

Step1: Calculate the number of valence - electrons

Sulfur (S) has 6 valence electrons, oxygen (O) has 6 valence electrons. For $[SO_{4}]^{2 -}$, the total number of valence electrons is $6 + 4\times6+2=32$ electrons.

Step2: Determine the central atom and bonding

Sulfur is the central atom. It forms 4 single - bonds with 4 oxygen atoms, using 8 electrons. The remaining $32 - 8 = 24$ electrons are placed as lone - pairs on the oxygen atoms.

Step3: Calculate the electron - domain geometry

The sulfur atom has 4 bonding pairs and 0 lone - pairs. According to the VSEPR (Valence - Shell Electron - Pair Repulsion) theory, the electron - domain geometry is tetrahedral when the central atom has 4 electron - domains (bonding pairs + lone - pairs).

Step4: Determine the molecular geometry

Since there are no lone - pairs on the central sulfur atom, the molecular geometry is also tetrahedral.

Answer:

1. Tetrahedral for both electron and molecular geometries