Question

In a mineral with chemical formula ATₓOₙ, the ionic radii of A and O are 1.12 Å and 1.40 Å, respectively. The co-ordination number of cation A is

Hint:

The co-ordination number can be estimated from the ionic radii ratio in ionic compounds. For ratios between 0.414 and 0.732, the co-ordination number is typically 6.

Answer 1

Step 1: Understanding the question.
The question is asking for the co-ordination number of cation A in a mineral, given its ionic radii. The co-ordination number is the number of nearest neighbors surrounding a central ion in a crystal structure.
Step 2: Analyzing the solution.
For an ionic compound with ionic radii of A = 1.12 Å and O = 1.40 Å, we can determine the co-ordination number using the radius ratio. The ratio of radii (rA/rO) is approximately 0.80, which corresponds to a co-ordination number of 6 in typical ionic structures.
Step 3: Conclusion.
The correct answer is 6, as it corresponds to the co-ordination number of cation A.