chemistry

SOME PHYSICAL PROPERTIES OF ALKALI METALS  ELEMENTS

Property	Elements
	Li	Na	K	Rb	Cs	Fr (Radioactive)
Atomic Number	3	11	19	37	55	87
Electronic Configuration	2s’	3s’	4s’	5s’	6s’	7s’

 

Atomic Mass		6.94	22.99	39.10	85.47	13.91	223
Metallic radius (pm)		152	186	227	248	265	375
Ionic radius (M+/pm)		76	102	138	152	167	180
Ionization enthalpy (kJ mol–1)	I	520	496	419	403	376	–
	II	7298	3562	3051	2633	2230	–
Electro negativity (Pauling Scale)		0.98	0.93	0.82	0.82	0.79
Density/g cm–3 (at 298K)		0.53	0.97	0.86	1.53	1.90
Melting point/K		454	371	336	312	302
Boiling point/K		1615	1156	1032	961	944
E°(V) at 298K for M+(aq) + e–→ M(s)		–3.04	–2.714	–2.925	–2.930	–2.927
Occurrence in Atmosphere		18*	227**	1.84**	78.12*	2.6*

*ppm (parts per million)               ** percentage by weight