Alkali Metals
- Alkali metals are the elements in Group 1 of the periodic table:
Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), Francium (Fr).
Properties
- Outer electrons → They all have 1 electron in the outer shell.
- Soft metals → Can be cut with a knife.
- Light → Some (like Li, Na, K) are less dense than water.
- Low melting points → They melt easily compared to other metals.
- Very reactive → React quickly with water and oxygen.
- Reactivity increases down the group → Li (least reactive) → Cs/Fr (most reactive).
Reactions
- With water → make an alkaline solution (metal hydroxide) + hydrogen gas.
Example: Sodium + Water → Sodium hydroxide + Hydrogen. - With oxygen → form oxides.
- With halogens → form salts (like NaCl).
Uses
- Lithium → batteries.
- Sodium → street lights, making soap.
- Potassium → fertilizers.
- Cesium → atomic clocks.
In short:
Alkali metals are soft, shiny, and very reactive metals with 1 outer electron. They react with water to form strong bases and become more reactive as you go down the group.