Explain the concept of Primary Valency and Secondary Valency as proposed by Alfred Werner.

(N/A) Alfred Werner prepared and characterized a large number of coordination compounds and studied their physical and chemical behavior. He was the first to formulate ideas about the structure of coordination compounds.
$1$. Primary Valency: These are ionizable valencies,generally satisfied by negative ions. They correspond to the oxidation state of the metal ion.
$2$. Secondary Valency: These are non-ionizable valencies,satisfied by neutral molecules or negative ions. They correspond to the coordination number of the metal ion.
In a series of compounds of cobalt$(III)$ chloride with ammonia,it was found that some chloride ions could be precipitated as $AgCl$ on adding excess $AgNO_{3}$ solution,while others remained bonded to the metal.
$1$ mol $CoCl_{3} \cdot 6 NH_{3}$ (Yellow) gave $3$ mol $AgCl$
$1$ mol $CoCl_{3} \cdot 5 NH_{3}$ (Purple) gave $2$ mol $AgCl$
$1$ mol $CoCl_{3} \cdot 4 NH_{3}$ (Green) gave $1$ mol $AgCl$
$1$ mol $CoCl_{3} \cdot 4 NH_{3}$ (Violet) gave $1$ mol $AgCl$

$Formula$	$Solution \text{ } conductivity$
$[Co(NH_{3})_{6}]Cl_{3}$	$1:3$ electrolyte
$[CoCl(NH_{3})_{5}]Cl_{2}$	$1:2$ electrolyte
$[CoCl_{2}(NH_{3})_{4}]Cl$	$1:1$ electrolyte

In these compounds,the atoms within the square brackets are directly bonded to the metal ion and represent the secondary valency,which is $6$ for cobalt in these examples.