Name: Variation of Atomic Radius in Periodic Table
Uploaded: 2019-07-19
Duration: 4 min 6 s
Description: The atomic radius is defined as the distance between the atom's nucleus and the outermost shell. But do you know how it varies in the periodic table? Let's find the answer in this video.

Question

Name the four blocks of elements in the periodic table and indicate the main difference in their electronic configurations. Give examples of each type. State at least four characteristics of each block.

Accepted Answer

Elements in the long form of periodic table are classified according to their electronic configuration. In the electronic configuration, the last electron enters to $s, p, d$ and $f$ -orbitals are classified as $s$ -block, $p$ -block, $d$ -block and $f$ -block respectively.
$s$ -Block: The general outer electronic configuration of this block is ${ns}^{1 - 2}$ . Examples: $Li, Na, K, Be, Mg, Ca, Sr$ , etc.

These elements have the following properties.

Highly electropositive metals.

Have very low ionisation enthalpy.

They all are strong metals (soft metals, i.e., low melting and boiling point)

They are good conductors of heat and electricity.

They are good reducing agents.

$p$ -Block: The general outer electronic configuration of this block is ${ns}^{2} {np}^{1 - 6}$ . Examples: $B, Al, C, N, O, P, S, Si, Ge$ , etc.

These elements have the following properties.

The ionisation enthalpies of these elements are higher than $s$ -block elements.

This block consists of metals, metalloids and non-metals.

The oxidising power of these elements increases left to right in a period.

Down the group their metallic character increases.

$d$ -block elements: The general outer electronic configuration of this block is $(n - 1) d^{1 - 10} {ns}^{1 - 2}$ . Examples: $Sc, Ti, Ag, Au, Fe, Cu, Ni$ , etc.

These elements have the following properties;

These elements are called transition elements, because they have properties in between representative elements.

These elements show complex forming properties.

These elements also show catalytic properties.

These elements show variable oxidation states.

These are good conductors of heat and electricity.

$f$ -Block: The general outer electronic configuration of this block is $(n - 2) f^{1 - 14} (n - 1) d^{0 - 1} {ns}^{2}$ . Examples: $Ce, Pm, Bk, Th, Lu, Lr$ , etc.

These elements have the following properties:

They are heavy metals and most of them are radioactive.

They also form coloured compounds.

They have high melting and boiling points.

Thy also show complex forming tendency.

Name the four blocks of elements in the periodic table and indicate the main difference in their electronic configurations. Give examples of each type. State at least four characteristics of each block.

Important Questions on Classification of Elements and Periodicity in Properties

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