Since "periodic table" chapter is not available so I have selected Acids,bases and salts
 
I have a duel pack of class viii & ix
 
Question 
 
Sodium and potassium have atomic numbers 11 and 13 respectively. They are separated by one element in the periodic table, and hav valency 1 and 3 respectively. Chlorine and potassium are also separated by one element in the periodic table (their atomic numbers being 17 and 19, respectively) and yet both haye valency 1. explain.

Asked by Shoumik | 27th May, 2015, 01:25: PM

Expert Answer:

Sodium and Potassium are metals which are placed in Group 1 of the Periodic table.
Sodium has atomic number 11 and electronic configuration: 2 , 8 , 1
Potassium has atomic number 19 and electronic configuration 2 , 8, 8, 1
Sodium and potassium are metals and they have a tendency to donate their one electron to non-metals to attain stable electronic configuration.
Sodium and Potassium after donating one electron acquire positive charge and their valency is 1.
On the other hand chlorine is a non-metal with atomic number 17 and electronic configuration 2, 8, 7.
It needs one electron to complete its stable configuration.
So it accepts one electron from metals and acquires negative charge and its valency is 1.

Answered by Vaibhav Chavan | 28th May, 2015, 01:37: PM