Group 1 metals are also called as alkali metals. These are the most reactive metals. They contain only one electron in its valence shell thus they form +1cations.
The alkali metals are good conductors, and they have a shiny, silvery appearance. In flame tests, lithium forms a candy-apple red colour, while sodium produces a yellow flame and potassium a lilac flame.
They react with hydrogen to form metal hydrides.
2M + H2
(Where M= Li, Na, K, Rb, Cs)
They react with halogens to form alkali metal halide salts, such as NaCl.
2Na + Cl2
They react with oxygen lithium forms oxides, sodium forms peroxides, and the other group 1 metals form superoxides.
4Li + O2
O (Lithium oxide)
2Na + O2
M + O2
Where M = K, Rb, Cs
Alkali metals react vigorously with water to produce hydroxide ions in solution, and hydrogen gas.
- An alloy with lead is used to make engine parts, an aluminium-lithium alloy is used in airplane construction and a magnesium-lithium alloy is used to make armour plates.
- Lithium metal is used in some thermonuclear reactions and to construct various types of batteries.
- Sodium-lead alloy was used to produce organo-lead compounds such as tetraethyl lead, which was used as an anti-knock agent in automobile fuel.
- Potassium has a variety of roles in biological systems. Potassium chloride is used as an agricultural fertiliser under the name ‘muriate of potash’.
- Cesium is used in the manufacture of photoelectric cells.