Which category of metals includes lithium, sodium, and potassium and is highly reactive with water?

Which category of metals includes lithium, sodium, and potassium and is highly reactive with water?

• A. Alkali metals
• B. Alkaline earth metals
• C. Transition metals
• D. Noble metals

Answer: (A)

Lithium, sodium, and potassium belong to alkali metals, a family in Group 1 of the periodic table. They have one valence electron, so they readily lose that electron to form a +1 ion. That easy loss drives their intense reactivity with water: when these metals meet water, they rapidly form a metal hydroxide and hydrogen gas, releasing a lot of energy and sometimes igniting the hydrogen. Because they react so readily with moisture and air, they’re stored under oil to keep them from reacting. Other metal groups don’t fit this pattern. Alkaline earth metals do react with water but not as vigorously and they have two valence electrons. Transition metals aren’t characterized by this kind of vigorous reaction with water, and noble metals are known for being unusually unreactive.

Lithium, sodium, and potassium belong to alkali metals, a family in Group 1 of the periodic table. They have one valence electron, so they readily lose that electron to form a +1 ion. That easy loss drives their intense reactivity with water: when these metals meet water, they rapidly form a metal hydroxide and hydrogen gas, releasing a lot of energy and sometimes igniting the hydrogen. Because they react so readily with moisture and air, they’re stored under oil to keep them from reacting.

Other metal groups don’t fit this pattern. Alkaline earth metals do react with water but not as vigorously and they have two valence electrons. Transition metals aren’t characterized by this kind of vigorous reaction with water, and noble metals are known for being unusually unreactive.