Name: Need for Classifying Elements
Uploaded: 2019-07-19
Duration: 8 min 18 s
Description: We all like things that are properly arranged and placed. What about the arrangement of elements? On what basis can they be arranged? Let us explore.

Question

Define the modern periodic law. Discuss the construction of long form of the periodic table.

Accepted Answer

The modern periodic law may be stated as "The physical and chemical properties of elements are the periodic functions of the electronic configurations of their atoms".

Construction of the long form of the periodic table:

The modern periodic table has eighteen vertical columns known as groups and seven horizontal rows known as periods.

Elements are arranged in the order of increasing atomic numbers in periods.

In groups, the elements are placed having similar electronic configuration. A group has a similar number of electrons in the outermost shell.

s-block elements: The elements with valence shell electronic configuration ${ns}^{1}$ and ${ns}^{2}$ are called s-block elements.

p-block elements: The elements with valence shell electronic configuration ${ns}^{2} {np}^{6}$ are called p-block elements.

The s and p block elements are together known as representative elements.

d-block elements: The elements with valence shell electronic configuration ${ns}^{2} {np}^{6} (n - 1) d^{1}$ to ${ns}^{2} {np}^{6} (n - 1) d^{10}$ are called d-block elements. These are also known as transition elements.

f-block elements: The elements in which orbitals are being filled in their f-orbitals are called f-block elements. These elements are also known as Inner transition elements.

Period Number	Filling up orbitals (subshells)	Maximum number of electrons, filled in all sub shells	Total number of elements in the period
$1$
$2$
$3$
$4$	$4 s$ , $3 d$ , $4 p$	$18$	$18$
$5$
$6$
$7$	$7 s$ , $5 f$ , $6 d$ , $7 p$	$32$	incomplete

Period number	Total number of elements	Elements from	Elements To	Total number of elements in s-block	Total number of elements in p-block	Total number of elements in d-block	Total number of elements in f-block
$1$
$2$
$3$
$4$
$5$
$6$
$7$

Define the modern periodic law. Discuss the construction of long form of the periodic table.

Important Questions on Classification of Elements-The Periodic Table

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