Which statement describes alkali metals?

• A. Very reactive, with one valence electron
• B. Inert and unreactive
• C. Have two valence electrons
• D. Noble gases

Answer: (A)

Alkali metals are the elements in Group 1 that have one electron in their outermost shell. That single valence electron is easily lost, so these metals form +1 ions and become highly reactive, especially with water. This makes the statement describing them as very reactive and having one valence electron the best fit. They are not inert and unreactive—their reactivity is a hallmark, unlike noble gases. They also do not have two valence electrons (that would describe alkaline earth metals), and they are not noble gases.