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Diagonal Relationships :

On moving diagonally across the periodic table, the elements show certain similarities in their properties which are quite prominent in some cases as shown below. This is called a diagonal relationship.

Classification of elements on the basis of electronic configuration:

From the view point of electronic configuration the elements can be subdivided into four major sub groups (Figure 1). They can be classified as s,p,d and f block elements.

1. s-block elements : These have two atoms and include groups I A & II A. They contain one or two electrons in their outer S-orbital. Strongly electropositive metals. The group I A elements are alkali metals. Elements with two electrons in the outer orbit are called alkaline earth metals.


2. p-block elements : The elements from groups III A to VII A are included in this type. These are generally non-metals. These elements are generally non-conductors with the exception being Silicon and Germanium which are semi-conductors.

3. d-block elements : These are the elements in which the last electron is placed in d-orbital of penultimate energy level. These elements are also known as transitional elements. All are metallic and have high melting and boiling points. Good conductors of heat and energy.

4. f-block elements : The transition elements in which pre-penultimate f-sub orbital is being filled up are called as inner-transition elements. There are two series of these elements :
1) Lanthanides & 2) Actinides. Their compounds are colored and are usually paramagnetic.

5. zero-group elements : Earlier these elements were known as inert or Noble gases. They are chemically unreactive. They are incapable of forming any chemical compounds.

Index

2.1 Classification of Elements
2.2 Introduction to the Periodic Table

Chapter 3





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