Question

Why phosphorus is termed as a typical element?

Answer 1

The third period elements( Na, Mg, Al,Si,P,S,Cl) are called the TYPICAL elements. they are called so because they represent properties of their own group. like if you want to study the properties of group 1, then you must better choose the sodium and u get the clue for others of its family, others are of its type, and hence these elements are called typical elements.

do not confuse this term with bridge elements(the elements that show diagonal relationship) because the concept behind them are not at all same, but sometimes people tend to confuse the terms.

the obvious question is then why not we call second period elements as typical??

the reason is that the scientists found some anomalous properties in period2 elements and thus they were not capable to represent the group. there are few reasoms for this anomaly

The reasons for differences in periodic properties and hence in chemical behavior are:

Small size of these atoms
High electronegativity
Large charge/radius ratio
this typical elements are also called REPRESENTATIVE elements.