Chapter : 7. Periodic Classification of Element
Periods in Periodic Table
Periods :
(1) The horizontal rows in the periodic table are called periods.
(2) There are 7 periods in the long form of periodic table
(3) The first period contains 2 elements, Hydrogen and Helium. They have only one shell.
(4) The second period contains 8 elements : Lithium Li(3), Beryllium Be(4), Boron B(5), Carbon C(6), Nitrogen N(7), Oxygen O (8), Fluorine F(9) and Neon Ne (10). The second period has 2 shells (K and L) and L shell is progressive filled.
(v) The elements of 3rd period are :
In 3rd period, 3rd shell (M-shell) is being progressively filled and there are three shells.
4th period has 18 elements
5th period has 18 elements
6th period has 32 elements
7th period has 32 elements
In periods, the number of valence electrons increases from left to right in s and p-blocks
Modern Periodic Table
(1) The horizontal rows in the periodic table are called periods.
(2) There are 7 periods in the long form of periodic table
(3) The first period contains 2 elements, Hydrogen and Helium. They have only one shell.
(4) The second period contains 8 elements : Lithium Li(3), Beryllium Be(4), Boron B(5), Carbon C(6), Nitrogen N(7), Oxygen O (8), Fluorine F(9) and Neon Ne (10). The second period has 2 shells (K and L) and L shell is progressive filled.
(v) The elements of 3rd period are :
In 3rd period, 3rd shell (M-shell) is being progressively filled and there are three shells.
4th period has 18 elements
5th period has 18 elements
6th period has 32 elements
7th period has 32 elements
In periods, the number of valence electrons increases from left to right in s and p-blocks
Modern Periodic Table
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