Why are Group 1 metals so reactive and what are they called?

Group 1 of the Periodic Table, or the Alkali Metals, include lithium, sodium, potassium, rubidium, caesium, and francium.  The columns of the Table reflect a "family" of elements; each member within the family has the same number of electrons in its outer shell, but those electrons are further from the center of the atom (nucleus) going down the column, as a general rule.  All atoms tend towards a completely full outer shell, some achieving this by shedding electrons, others by gaining them. In the case of the Alkali family, each possesses a single electron in its outermost shell, which they want to "give away" to achieve that more stable  outer shell, which makes them very reactive with other atoms or compounds that want an additional electron in their outer shell to achieve stability.