Light Metals

low-density metals (see Table 1). Light metals are widespread in nature (more than 20 percent by mass), but because of their high chemical activity they exist only in the form of extremely strong compounds.

Table 1. Light metals
	*Chemical symbol*	*Atomic number*	*Density at 20°C (kg/m³)*
Lithium.............	Li	3	534
Beryllium............	Be	4	1,847.7
Sodium.............	Na	11	968.4
Magnesium..........	Mg	12	1,739
Aluminum...........	Al	13	2,698.9
Potassium...........	K	19	862
Calcium............	Ca	20	1,540
Titanium............	Ti	22	4,505
Rubidium............	Rb	37	1,532
Strontium...........	Sr	38	2,630
Cesium.............	Cs	55	1,900
Barium.............	Ba	56	3,760

Light-metal metallurgy first developed in about the mid-19th century. The main methods of producing light metals are electrolysis of fused salts, metallothermy, and electrothermy. Light metals are used mainly in the manufacture of light alloys. The most important light metals are aluminum, magnesium, titanium, beryllium, and lithium.

REFERENCES

Beliaev, A. I. Metallurgiia legkikh metallov, 6th ed. Moscow, 1970.