Answer: Oxidation state (ionisable valence).
- A Oxidation state (ionisable valence)
- B The coordination number, which Werner instead termed secondary valence
- C A separate secondary valence distinct from the primary valence
- D Simply the total number of ligands bound to the metal centre
Correct answer: A. Oxidation state (ionisable valence)
Explanation: Werner's primary valence = oxidation state (charged bonds satisfying electrovalence). Secondary valence = coordination number.
The three common coordination geometries: octahedral (6 ligands), tetrahedral (4 ligands), and square planar (4 ligands in one plane).
Concept context
Study of compounds where a central metal atom is bonded to surrounding ligands. Covers nomenclature, types of isomerism, bonding theories (VBT, CFT), and applications in medicine, photography, and industry.