Alkali metals have a valency of +1. With only a single covalent bond, the metals are weakly bound. The metals are soft, so that they can be cut with a knife. They have low density and lithium, sodium and potassium are all light enough to float on water. They react with non-metals to form salts. These salts are white, crystalline and soluble in water. Under conditions where alkali metals react with water the result is an alkaline solution. They have a characteristic reaction with oxygen such that oxygen will combine with lithium to form lithium oxide (Li2O).

Elements of the Periodic Table
Elementsort icon Atomic numbersort icon Atomic weightsort icon Boiling pointsort icon Densitysort icon Heat fusionsort icon Heat vapoursort icon Melting pointsort icon Specific heat capacitysort icon Thermal conductivitysort icon
Caesium 55 132.9 963.16° K 1900 kg/m³ 2.09 kJ/mol 68.26 kJ/mol 301.86° K 5.3 W/m/K
Francium 87 223.02 0 J/kg/K
Hydrogen 1 1.01 20.46° K 71 kg/m³ 13.96° K
Lithium 3
Potassium 19 39.1
Rubidium 37 85.47 961.16° K 1530 kg/m³ 2.3 kJ/mol 75.8 kJ/mol 312.06° K 8 W/m/K
Sodium 11 22.99 1165.16° K 970 kg/m³ 2.6 kJ/mol 101.01 kJ/mol 370.96° K 134 J/kg/K 21.8 W/m/K
Amazon Books
Image of Mendeleev on the Periodic Law: Selected Writings, 1869-1905
Author: Dmitri Ivanovich Mendeleev
Publisher: Dover Publications Inc. (2005)
Binding: Paperback, 320 pages