The term "family metals" is not a standard term in chemistry. It's likely you're referring to groups of elements on the periodic table, which are sometimes referred to as "families."

If you're asking about the most reactive group of metals, that would be the alkali metals (Group 1). These metals, including lithium (Li), sodium (Na), potassium (K), rubidium (Rb), cesium (Cs), and francium (Fr), are highly reactive due to their single valence electron, which they readily lose to form positive ions.

Here's why they're considered the most reactive:

* Low ionization energy: It takes very little energy to remove their single valence electron.

* Large atomic radius: Their outermost electron is far from the nucleus and weakly held.

* Low electronegativity: They readily lose electrons to become cations, making them good reducing agents.

Important Note: The reactivity of alkali metals increases as you move down the group. This means that cesium is the most reactive of the alkali metals, followed by francium. However, francium is a radioactive element and very rare, so cesium is considered the most reactive element in this group.