Question

How do the number of valence electrons differ across a period?

Answer 1

The number of valence electrons increases sequentially.......

Explanation:

The number of valence electrons increases sequentially.......across the Periodic Table, from left to right as we face the Table.

And take the first Period; hydrogen has ONE valence electron; and helium has TWO valence electrons. And clearly the number of valence electrons influences the reactivity of the element.

And start a new Period, lithium (`"Group 1"`) has ONE valence electron; beryllium (`"Group 2"`) has TWO valence electrons; boron (`"Group 13"`) has THREE valence electrons; carbon (`"Group 14"`) has FOUR valence electrons......................