Question

the horizontal rows on a periodic table have the same question #elsic | socratic atomic mass atomic number/ protons chemical reactivity number of energy levels/ rings number of neutrons number of total electrons number of valence electrons

Explanation:

Horizontal rows (periods) in the periodic table have the same number of energy levels (electron shells). Atomic mass, protons (atomic number), neutrons, total electrons, valence electrons, and reactivity vary across a period.

Answer:

number of energy levels/ rings