Page 1 - Microsoft Word - Module-4

SUBJECT – CHEMISTRY

S-BLOCK ELEMENTS

SUB TOPICS – GENERAL CHARACTERISTICS OF THE

COMPOUNDS OF ALKALINE EARTH METALS, ANOMALOUS

BEHAVIOUR OF Be, DIAGONAL RELATIONSHIP BETWEEN Be

AND Al, SOME IMPORTANT COMPOUNDS OF Ca, BIOLOGICAL

IMPORTANCE OF Mg AND Ca

KEY NOTES:

GENERAL CHACTERISTICS OF COMPOUNDS

OF ALKALINE EARTH METALS

Oxides and hydroxides:

 BeO is amphoteric whereas others are basic. They

react with water forming hydroxides.

MO + H O  M(OH) M= Alkaline earth metal
2;
2
 The solubility in water, basic character and thermal

stability decreases down the group.

 Be (OH) react with acids as well as alkalis and thus
2
amphoteric in nature.

Be (OH) + OH-  [Be (OH) ] -
2
4
2
Beryllate ion

Be (OH) + 2HCl+2H O[Be (OH) ] Cl 2
4
2
2