NCERT Question 12 - Chapter 4 Class 9 - Structure of Atom

If Z = 3, what would be the valency of the element? Also, name the element.

Answer

• Z represents the atomic number of an element.
• Z = 3 means, atomic number = 3
• That is, number electrons/protons = 3
• 3 electrons are accommodated different shells as follows,

K Shell = 2 e ^-

L Shell = 1 e ^-

• Now, since the L shell has only 1 e ^- , it will lose it to become more stable.
• Since the atom loses 1 e ^- , its valency will be 1 .

We know that Atomic Number of Lithium is 3,

Hence, the element is Lithium (Li).