Question

how does valency of an element vary across a period​

Answer 1

Answer:

Answer: The valency of an element is dependent on the number of electrons in the outermost shell of the electron. In a group all constituting elements will have the same valency because they all have the same number of electrons in the outer shells. Across the a period, the number however increase by 1.

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Answer 2

Valency of an element first increases and then decreases, across a period of the periodic table.

• Valency is actually the number of total electrons present in te outermost orbit of an element's atom.

• Now, excluding the transition metals (because they show variable valencies), there are 8 elements in a single period of the modern periodic table.

• Now,across these 8 elements the valency goes from +1 to +4 (or-4) in the first 4 elements of these 8 elements.

• And,from the 5th element to 7th element of these 8 elements,the valency goes -3 to -1.

• Finally, for the 8th element which are mainly the noble gases,the valency becomes zero.