Alkali Metals
Definition and meaning of Alkali Metals in chemistry.
Alkali metals are the highly reactive elements in Group 1 of the periodic table, including lithium, sodium, potassium, rubidium, cesium, and francium. Each has a single valence electron in its outermost electron shell.
In more detail
All alkali metals are soft, malleable metals with relatively low densities and low melting points. They have exceptionally low ionization energies, making them intensely reactive with both oxygen and water, and are rarely found in nature in pure metallic form. These elements readily lose their single valence electron to form stable +1 cations. Reactivity increases dramatically down the group as atomic size increases and the valence electron becomes further from the nucleus, making francium the most reactive element known.
Key facts
| Group | Group 1 of the periodic table |
|---|---|
| Valence electrons | 1 |
| Common oxidation state | +1 |
| Field | Inorganic Chemistry |
Sodium metal reacts vigorously with water: 2Na + 2H2O → 2NaOH + H2↑, producing sodium hydroxide and hydrogen gas that often ignites from the heat of reaction.
Frequently asked questions
Why are alkali metals stored under mineral oil or inert atmosphere?
Alkali metals are so reactive that they will corrode in air by reacting with oxygen and moisture, so they must be isolated from both to prevent degradation.
What is the most abundant alkali metal in Earth's crust?
Sodium is the most abundant alkali metal, comprising about 2.8% of Earth's crust and occurring widely in minerals like halite and feldspar.