A valance electron is one that is associated with an atom. The valence orbit is the one that electron travels in.
In fact an electron has no valency, though it is equal to a -1 (minus one) charged anion like Cl-, having a valency of -1
The valency of hydrogen is +1 because it has a tendency to lose an electron while combining with an Elelment. This gives it a positive valency.
The valency of lithium is 1. It has one valence electron in its outer shell.
The valency of iodide is -1. This means that iodide typically gains one electron to achieve a stable electron configuration in chemical reactions.
Mercury
If this is true then the answer will lie in it's electron count.
The valency of sodium is +1
-1 valency
The valency of fluorine is 1. It typically forms one bond by gaining one electron to achieve a full outer electron shell.
single valency. last orbit has 7 electrons.
The symbol for mercury is Hg and it has a valency of 1 or 2, depending on the compound it is in. In most cases, mercury exhibits a valency of 2.