Characteristics of periods
The systematic distribution of electrons in different shells of an atom is known as electronic configuration.
But, according to duplet and octet rule, K-shell can hold maximum 2 electrons and the other shells can hold 8 electrons. So, to overcome the contradiction, between 2n2rule and duplet and octet rule, the concept of sub shell is introduced.
According to this concept, different shell has their sub shell named as s, p, d and f sub shell and they can hold 2,6,10 and 14 electrons respectively.
|Shell||Sub Shell||No of electron|
These metals are soluble in water and form metallic hydroxides and evolve hydrogen gas. These hydroxide are called alkalis. Therefore the elements of group IA are called alkali metals.
Sodium has one valence electron. Therefore, it has tendency to lose its valence electron during chemical reaction to be octet. So, it is called active metal.
Electronegativity is a measure of the tendency of an atom to attract a bonding pair of electrons. Fluorine (the most electronegative element) is assigned a value of 4.0
The horizontal rows of periodic table are called periods.
On moving left to right along the period the metallic character goes on decreasing and non-metallic character goes on increasing.
On moving from left to right in periodic table the electronegativity ______.
increases for certain time
On moving from left to right in periodic table the atomic size ______.
both increases and decreases
D shell of electronic configuration can hold _______.
none of above
The electronic configuration of an atom with atomic number 8 is ______.
The order of filling orbitals is ______.
4p, 4s, 3d, 3p, 3s, 2p, 2s, 1s
1s, 2s, 2p, 3s, 3p, 3d, 4s, 4p
none of above
1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p