Coordination Compounds: common misconceptions

If your child says… “Both valencies must be six.”

Ask together

Do six neutral ammonia molecules cancel cobalt’s positive charge?

What’s true

Primary valency describes oxidation state; secondary valency counts directly attached donor atoms.

If your child says… “The Roman numeral gives the whole compound’s charge.”

Ask together

Would a neutral compound need III if the numeral described its total charge?

What’s true

The Roman numeral records the metal’s oxidation state.

If your child says… “Cis and trans are just different viewing angles.”

Ask together

When the whole diagram turns, do neighbouring chlorides stop being neighbours?

What’s true

Turning a whole complex preserves which ligands are neighbours.

If your child says… “Six paired bonds mean every electron is paired.”

Ask together

Which incoming ammonia pair enters an already occupied chromium orbital?

What’s true

Paired bonding electrons can coexist with unpaired metal electrons in other orbitals.

If your child says… “Electrons must fill every orbital before any pairing happens.”

Ask together

Which costs less energy here: pairing below or moving above?

What’s true

Pairing is favoured when the orbital energy gap exceeds the pairing energy.

If your child says… “Back-donation strengthens every bond in a metal carbonyl.”

Ask together

Would adding electrons to an antibonding orbital strengthen the carbon–oxygen bond?

What’s true

Donation and back-donation involve different orbitals and have different effects on carbon–oxygen bonding.