# When moving across a row in the Periodic Table, what increases?

$Z$, atomic number, increases sequentially, and thus does nuclear charge.
Because $Z$, the number of positively charged, massive nuclear particles, increases across the row from left to right as we face the Table, nuclear charge increases. Because nuclear charge increases, the atomic radii, defined by the orbit of the valence electrons, DECREASE, as the increased nuclear charge exerts a pull on the valence electrons.