Which statement best describes the reactivity of potassium compared to lithium and sodium?

Potassium is indeed more reactive than sodium, and this increased reactivity can be attributed to its position in the alkali metal group of the periodic table. As one moves down the group from lithium to sodium to potassium, the reactivity of the metals increases. This is because the outermost electron in potassium is further away from the nucleus compared to that in sodium. The increased distance results in a weaker electrostatic attraction between the outer electron and the positively charged nucleus, making it easier for potassium to lose that electron during a chemical reaction.

Furthermore, potassium's larger atomic radius also contributes to its higher reactivity, as the shielding effect from inner electron shells reduces the effective nuclear charge felt by the outermost electron. Consequently, potassium reacts more rapidly than sodium when exposed to water or halogens, producing a vigorous reaction, which is observed in its characteristic behavior in chemical reactions.