S block elements

All the existing elements in the modern periodic table is divided into four main segments or blocks. A block consists of groups of elements having similar electronic configurations and properties. These are called s block, p block, d block and f-block.

S block elements on modern periodic table

The elements in which the last electron enters the s-orbital of their outermost energy level are called s-block elements. It consists of elements of group 1 of modern periodic table and group 2 of modern periodic table having the ground state electronic configurations of outermost shell as ns¹ and ns² respectively (where n stands for outermost energy shell). The elements of first group on modern periodic table corresponding to ns1 configuration are called alkali metals while the elements of group 2 on modern periodic table corresponding to ns² configuration are called alkaline earth metals. Thus the general electronic configuration of s-block elements may be expressed as : ns^{1 – 2}


General characteristics of s-block elements

1. They are soft metals having low melting and boiling points.
2. They have low ionization enthalpies.
3. They are very reactive and readily form univalent ions (alkali metals) or bivalent ions (alkaline earth metals) by losing one or two valence electrons respectively.
4. Most of them impart characteristic colours to the flame.
5. They mostly form ionic compounds except lithium and beryllium.

Test your understanding and answer these questions:

1. What are alkali metals?
2. What are alkaline earth metals?
3. What is the general electronic configuration of s block elements?