Question

how to find valency of elements ?

Answer 1

The periodic table table is organized in part by valence electron. In the table, along the top of the Periodic Table are numbers (0-7). These correspond to valency. The noble gases (far right) have 8 electrons in their valence shell and, as the shell is full, have a valency of 0. The alkali metals (far left) have one electron in their outer shell and a valency of 1, shown by the 1 above it. Valency can therefore be easily determined by a Periodic Table for all elements except transition metals.