A transition element- a d-block element that can form at least one stable ion with a partially filled d-subshell. The d-subshell can hold 10 electrons. Scandium and Zinc aren’t transition metals because they don’t have ions in the d-subshell.
Dative covalent bond (coordinate bond)- A covalent bond formed when one atom provides both of the shared electrons.
Coordination number- the number of coordinate bonds that are formed with the central metal ion in a complex ion.
A complex ion's coordination number depends on the number of bonds formed with the ligands not the number of ligands. So, a complex ion that has 3 bidentate ligands will have a coordination number of 6 (3 ligands each forming 2 bonds).
Ligand- An atom, ion or molecule that donates a pair of electrons to a central metal ionin a complex ion.
Complex ion- A metal ion surrounded by coordinately bonded ligands.
Monodentate Ligands- A ligand that can only form one coordinate bond and donates 1 electron pair to a metal ion.
Bidentate Ligands- A ligand that can form two coordinate bonds and donates 2 electron pairs to a metal ion.
Multidentate Ligands- A ligand that can form three or more coordinate bonds.
