S-Block Elements and their Properties

The s-block elements belong to Group 1 and Group 2 in the periodic table. The elements of Group 1 are called alkali metals, and the elements of Group 2 are called alkaline earth metals. They form alkalies on reacting with water, which are called alkaline metals and alkaline earth metals. They have one or two s-electrons in their valence shells and are highly reactive. They form several compounds with various other elements, a lot of which have significance in human life and the processes of nature. This is why it is essential to study s-block elements and their properties.

S-block elements and their properties

The elements of the s-block are as follows: Lithium, Sodium, Potassium, Rubidium, Caesium, Francium, Beryllium, Magnesium, Calcium, Strontium, Barium, and Radium. Some of their properties are as follows:

1. Abundance: Sodium and potassium are the seventh and eighth most abundantly found elements in nature, and they are a part of the s-block elements in Group 1. Other elements of the block are not as common as the above two. From group 2, magnesium is relatively abundant in nature.

2. Valence electrons: The valence shells of s-block elements have either 1 or 2 electrons.

3. Nature of compounds: the compounds that the elements of the s-block form are primarily metallic.

4. Diagonal relationship: This means that the first element of one group resembles the second element of the next group. There is a resemblance of elements that are diagonal to each other.

5. Anomalous behaviour: the first elements of both groups 1 and 2 differ from the other members of the block due to the following reasons –

• • Size: the atomic and ionic size of these two elements, lithium, and beryllium, is much smaller than the rest of the group elements.

  • Electronegativity: Most elements of the s-block are highly electropositive lithium, and beryllium is electronegative.

  • No d-orbitals: These two elements do not possess d-orbitals which can be used to form bonds.

6. Oxidation state: the oxidation state of Group 1 elements is +1, and the oxidation state of Group 2 is always +2.

7. Electronic configuration: All the inner shells of these elements are complete. They have an electronic configuration of the type. 

8. Occurrence: the elements of the s-block in the periodic table are highly reactive and therefore are found in compounds with other elements in nature.

S-block elements and their properties: Alkali metals

Excluding hydrogen, the alkali metals are as follows: lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr). They have the  following properties:

1. Atomic and ionic radii: The atomic and ionic radii size increases as we go down the group. This means that the radii increase when going from Li to Cs. However, the cationic radius is smaller than the atomic radius because the alkali metals lose an electron to form a cation. 

2. Hydration enthalpy: The tendency to become hydrated increases with the decrease in the size of the ion. Higher the tendency to get hydrated higher the hydration enthalpy. So the hydration enthalpy of alkali metals decreases as one goes down the group because the ion size increases. So the hydration enthalpy order is as follows – Li>Na>Rb>Cs.

3. Electronic configuration:  is the representation of the general electronic configuration of alkali metals. ‘n’ is the valence shell.

4. Ionisation enthalpy: The ionisation enthalpy decreases from Li to Cs, and it is generally low across the period. This is because the valence s-electron becomes easier to donate as the size of the element increases. The increase in size also makes the force of attraction with the nucleus weaker.

S-block elements and their properties: Alkali earth metals 

1. Metallic character: Alkali earth metals show a stronger metallic character because they form stronger bonds. This is because of the presence of two s-electrons

2. Ionisation enthalpy: These elements have a relatively larger atomic size. So they generally have low ionisation enthalpies.

3. Electronic configuration: the general electronic configuration of alkaline earth metals can be represented by 

4. Atomic and ionic radii: When compared to alkali metals, alkaline earth metals have a smaller atomic and ionic size. This size increases as the atomic number increases. 

5. Hydration enthalpy: Since the size of alkaline earth metals is smaller than alkali earth metals, they have higher hydration enthalpy than alkali metals.

Conclusion

S-block elements and their properties are an important study in chemistry because they form so many compounds of importance with other elements. The elements found in the s-block of the periodic table are relevant in the fields of medical sciences, metallurgy, and various other areas of industrial importance. Magnesium and calcium are of particular importance in biology since they form a part of salts and enzymes necessary for the functioning of various animals.