Question

the number of valence electrons ------- by 1 as you move across the period. increases decreases

Explanation:

In the periodic table, as we move across a period (from left to right), the number of valence electrons of elements increases by 1. For example, in period 2, lithium (Li) has 1 valence electron, beryllium (Be) has 2, boron (B) has 3, and so on, until neon (Ne) with 8 valence electrons. This is because each element across a period has one more proton and one more electron than the previous element, and the outermost (valence) shell gains one electron at a time as we move from left to right in a period.

Answer:

increases