Occurrence and isolation

          Alkali metals are reactive and they are not found in nature as free metals.Sodium and potassium are relatively more abundant than the metals in this group. Na is present as a salt (sodium chloride, NaCl) in huge quantities in underground deposits (salt mines), in seawater and other natural waters. Potassium salts are found naturally in seawater, and as carnality, KCl-MgCl₂-6H₂O or ptash (KOH). The concentrations of Na⁺ and K⁺ions in seawater are 10,800 and 590ppm, respectively.

Sodium and lithium are obtained by the electrolysis of their molten chloride. For example.

During electrolysis Na⁺ ions are reduced to Na metal and chloride ions are oxidised to chlorine gas.

Potassium is made by the reaction of sodium vapour with molten/fused KCl at 850⁰C.

Rubidium and cesium are made by the reduction of their chlorides with calcium metal at 800⁰C.

All isotopes of francium are radioactive.

Some properties of alkali metals

           In this session, we will mainly concentrate on the chemistry of Na, K, and Li. The elements of Group 1 are soft metals and they conduct electricity and heat. Table 1 provides you with some of the physical data of Group 1 elements. As one would expect the ionic radius, r(M⁺), increases as you go down the group. The melting point (m,p) decreases from Li to Cs. Alkali metals have low densities and the densities (d) of Li, Na, and K are less than that of water thus these metals float on water. 

Some properties of group 1 elements

	R(M+)/pm	En Configuration	m.p./0C	d/gcm-3	E0	IE1 kjmol-1	IE2 kjmol-1
Li (Litium)	60	2s1	181	0.53	-3.04	520	7590
Na (Sodium)	95	3s1	98	0.97	-2.71	496	4560
K (Potasium)	133	4s1	63	0.86	-2.94	418	3060
Rb (Rubidium)	148	5s1	39	1.53	-2.94	401	2630
Cs (Caesium)	169	6s1	29	1.90	-3.03	376	2430