Chemistry Class 11 NCERT Solutions: Chapter 2 Structure of Atom Part 7

Q: 20. Calculate the wavelength of an electron moving with a velocity of Equation .

Answer:

According to de Broglie’s equation,

Image of Broglie equation for Structure of atom

Image of Broglie Equation

Image of Broglie equation for Structure of atom

Equation

Where,

Equation

Equation

Equation

Equation

Substituting the values in the expression of λ

Equation

Equation

Hence, the wavelength of the electron moving with a velocity of Equation

Q: 21. The mass of an electron is Equation If its Equation J, calculate its wavelength.

Answer:

From de Broglie’s equation,

Equation

Given,

Kinetic energy (K.E) of the electron Equation

Equation

Image of Kinetic Energy for Structure of Atom

Image of Kinetic Energy

Image of Kinetic Energy for Structure of Atom

Equation

Equation

Equation

Equation

Substituting the value in the expression of Equation

Equation

Equation

Hence, the wavelength of the electron is Equation

Q: 22. Which of the following are isoelectronic species i.e., those having the same number of electrons?

Image of Isoelectronic Species for Structure of Atom

Image of Isoelectronic Species

Image of Isoelectronic Species for Structure of Atom

Equation

Answer:

Isoelectronic species have the same number of electrons.

Number of electrons in sodium Equation

Number of electrons in Equation

A positive charge denotes the loss of an electron.

Similarly,

Number of electrons in Equation

Number of electrons in Equation

Number of electrons in Equation

A negative charge denotes the gain of an electron by a species.

Number of electrons in sulphur Equation

Equation

Equation

Hence, the following are isoelectronic species:

Equation

Equation

Explore Solutions for Chemistry

Sign In