Write the formula for a complex formed between ag and nh3, with a coordination number of 2.

Combination number 2 for silver means that it bonded to two species in the complex, in this way:

- Ag -

NH3 has coordination number one, which mean tha it only bonds to one speciesÑ

NH3 -

So, the complex is NH3 - Ag - NH3.

=> Molecular formula: Ag [NH3]2, now if you count the oxidation numbers you get:

 (2+) + 2*(-3) + 6(+1) = +2  - 6 + 6 = +2. So the complex has a net 2 positive charge, which gives the final fomula:

[Ag (NH3)2 ] (2+), where the final (2+) is a superscript that tells the charge of the complex.