Question

For tetrahedral coordination, the radius ratio (r₊/r₋) should be ______.

Options

• 0.155−0.225

• 0.225−0.414

• 0.444−0.732

• 0.732−1

Answer 1

For tetrahedral coordination, the radius ratio (r₊/r₋) should be 0.225−0.414.

Explanation:

In tetrahedral coordination, a cation is surrounded by 4 anions placed at the corners of a tetrahedron. For a cation to just fit into the tetrahedral void without distorting the structure, the radius ratio r₊/r₋ must lie between 0.225 to 0.414. This range ensures stable tetrahedral coordination geometry in ionic solids.