How does the position of an element in the periodic table correlate with its chemical reactivity?

Elements in the same column, or group, share similar outer‑electron patterns, so their reactions follow a trend: the further right you go, the less likely they are to lose electrons, making them less reactive. Down a column, atoms get bigger and their outer electrons are farther from the nucleus, so they are easier to lose or gain electrons, increasing reactivity. For example, sodium (Na) in group 1 is very reactive because its single outer electron is far from the nucleus and can be lost easily, while potassium (K) below it is even more reactive for the same reason. Thus, moving left to right across a period, atoms become more stable and less reactive, whereas moving down a group, atoms become larger and more reactive. This simple pattern lets chemists predict how a metal or nonmetal will behave in reactions.