In the periodic table the s–block is the block in which the alkali and alkaline earth metals are present. The s–block elements have the differentiating or the outermost electron(s) in the ns–orbital.
Elements in which all inner electron shells are completely filled, and the last electron enters the s–orbital of the outermost shell, are called s–block elements. Thus, for s–block elements, the differentiating electron enters the ns–orbital. Therefore, the outermost electronic configuration of the s–block elements is ns1 or ns2, all inner orbitals being completely filled. In modern periodic table s–block elements are placed in first two groups &ndash Group 1 or IA Group and Group 2 or IIA Group.
Group 1 elements are called alkali metals. Alkali metals are named after the Arabic word ‘al–qis’, meaning plant ash because the ash of plants is rich in the carbonates of sodium and potassium.
Group 2 elements are called alkaline earth metals because of the alkaline (basic) nature of their oxides, for the basic solutions the elements form in water and as these elements are naturally found in the earth's crust.
Group 1 and 2 elements provide the best example of regular trends with no significant exceptions. All the elements in the group 1 – Lithium (Li), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (Cs), radioactive Francium (Fr). Mnemonic:
Lilly and Nasty Kids Rub the Cats Fu r
Group 2 – Beryllium(Be), Magnesium(Mg), Calcium (Ca), Strontium (Sr), Barium (Ba), radioactive Radium (Ra) are very reactive metals. Mnemonic:
Beer Mugs Can Serve Bar Rats