How to calculate co-ordination number??

The coordination number of an atom in a molecule is the number of atoms bonded to the atom.The coordination number describes the number of neighbor atoms with respect to a central atom.

Example: The coordination number of diamond is 4, as each carbon atom rests at the center of a regular tetrahedron formed by four carbon atoms.

Steps for identifying the coordination number of a coordination compound.

1.  Identify the central atom in the chemical formula. Usually, this is a transition metal.
2.  Locate the atom, molecule, or ion nearest the central metal atom. To do this, find the molecule or ion directly beside the metal symbol in the chemical formula of the coordination compound. If the central atom is in the middle of the formula, there will be neighboring atoms/molecules/ions on both sides.
3.  Add the number of atoms of the nearest atom/molecule/ions. The central atom may only be bonded to one other element, but you still need to note the number of atoms of that element in the formula. If the central atom is in the middle of the formula, you'll need to add up the atoms in the entire molecule.
4.  Find the total number of nearest atoms. If the metal has two bonded atoms, add together both numbers,