Complex Ion Formation
Complex ions are metals in the center with other molecules or ions surrounding it. The surrounding molecules are called ligands. If there is an aluminum ion on its own and later bonds with six water molecules, empty orbitals are created when the ion become Al3+. The orbitals reorganize themselves into orbitals with uniform energy levels. Six orbitals are created, and six water molecules are bonded to the central aluminum ion. The number of coordinate bonds the central metal makes is called the coordination number. Although in this case the number of ligands and the coordination number is the same, it is not always the case.
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