Final answer:
The reactivity of metals increases from right to left on the periodic table due to an increase in atomic size and a decrease in ionization energy and electronegativity, which makes it easier for metals to lose electrons and thus be more reactive.
Step-by-step explanation:
The reactivity of metals increases from right to left across the periodic table primarily due to the increase in atomic size and the decrease in ionization energy as you move to the left in a period. The larger atomic size means that the valence electrons are further from the nucleus and more easily lost, making the metal more reactive. Additionally, decrease in electronegativity also contributes to this trend, as elements to the left tend to hold onto their electrons less tightly compared to those on the right.