s-block elements: 

Elements in which last electron enters into s-subshell are called s-block elements. It contains group I elements (Alkali metals) and group II elements (Alkaline earth metals)

1st group elements lose one electron during chemical combination. Therefore its oxidation state is +1. 

2nd group elements lose two electrons from valence shell during chemical combination and their oxidation state is +2. 

The highest shell number in a sub-shell electronic configuration is the period number of that element.

1. Group number characteristics = no.of electrons in valence sub-shell. 

2. s block ionization energy & electro negativity decreases downwards. 

3. Metallic character & reactivity increases downwards. 

4. Lose electrons during chemical combination j and they form ionic compounds. Their oxides and hydroxides are basic. Their atomic radii are high in a period.

p-block elements: 

• Last electron enters into p-subshell. 
• Group 13 -18 elements. 
• Highly reactive elements are nonmetals – group 17, 
• These are elements with positive and negative oxidation state.

Group number of p-block elements = electrons in last p-subshell + 12 

d-block elements: 

• Last electron enters into penultimate d-subshell 
• Known as transition elements. 
• Metals 
• Shows similarity in group and period. 
• Variable oxidation states. 
• Form coloured compounds.

Group = electrons in ‘d’-subshdl + electrons in s-subshell. 

f-block elements:

• Last electron enters into antepenultimate f sub-shell. 
• Contains Lanthanoids and Actinoids. 
• Variable oxidation state. 
• Most of the Actinoids are radioactive. 
• Most of the elements are artificial. 
• U, Th, Pu are used in nuclear reactors. 
• Some elements are used as catalyst in pet-roleum industry.