Li · Na · K · Rb · Cs · Fr
That outer electron is relatively easy to lose, so these metals commonly form +1 ions. Their reactivity generally increases down the group. Pure sodium and potassium react readily with air and especially with water.
The contrast between a pure element and its compounds matters. Sodium metal is highly reactive; sodium chloride is ordinary table salt. Chemistry depends on how atoms are bonded and charged, not simply on the names of the elements present.
Lithium is strongly associated with rechargeable batteries. Sodium and potassium are also essential in biology as ions, where they help cells maintain electrical gradients and transmit signals.