Is variable valency (promotion rule) used to know only if an compound exists or not??
or does it have any other application too?? please help
Answers
Answer:
I don't know
Explanation:
Sorry because I have not read this topic in my school
Answer:
What is Valency?
Valency is the combining capacity of an element. The number of electrons donated or accepted by an atom of an element so as to have electronic configuration of nearest noble gas is called its valency.
What is Variable Valency?
Sometimes, because of different conditions under which a chemical reaction takes place, the valency of the same element changes. Thus metals like lead, tin, copper, mercury, iron etc exhibit variable valency.
Normally, the metals donate electrons from their valence shell, so as to form positively charged ions. However, some metals lose electrons from the shell next to the valence shell. In such a situation the element exhibits more than one electropositive valency. Such elements are said to have variable valency.