Structure of the Atom NCERT Solution, study material, CBSE Notes

NCERT Solution: Structure of the Atom

Find out the valency of the atoms represented by the Fig. 4.3 (a) and (b).

Atom ‘a’ has zero valency; while atom ‘b’ has a valency of 1.

One electron is present in the outer most shell of the atom of an element X. What would be the nature and value of charge on the ion formed if this electron is removed from the outer most shell?

Single and positive charge (+1).

Write down the electron distribution of chlorine atom. How many electrons are there in the L shell? (Atomic number of chlorine is 17).

2, 8, 7. The L shell has eight electrons

In the atom of an element X, 6 electrons are present in the outermost shell. If it acquires noble gas configuration by accepting requisite number of electrons, then what would be the charge on the ion so formed?

This element needs to gain two electrons in order to acquire noble gas configuration. So, the charge on ion would be – 2.

What information do you get from the Fig. 4.4 about the atomic number, mass number and valency of atoms X, Y and Z? Give your answer in a tabular form.

In response to a question, a student stated that in an atom, the number of protons is greater than the number of neutrons, which in turn is greater than the number of electrons. Do you agree with the statement? Justify your answer.

Student is giving wrong statement. Number of protons can never be more than that of neutrons. It can be equal to or less than the number of neutrons. Number of electrons and protons is always equal in an atom.

Calculate the number of neutrons present in the nucleus of an element X which is represented as ³¹₁₅X

Mass number = No. of protons + No. of neutrons = 31

∴ Number of neutrons = 31 – number of protons

= 31 – 15 = 16

Match the names of the Scientists given in column A with their contributions towards the understanding of the atomic structure as given in column B