Questions - Answers

4. What is node and nodal plane? How many nodal planes are possible for 2p and 3d orbitals?

A: The point where the probability of finding electron is called nodal point or "node". The plane passing through node is called "nodal plane".

number of nodal planes = l

nodal planes for 2p = 1

nodal planes for 3d = 2
 

5. Explain briefly Planck's quantum theory.

A: Black body radiation was successfully explained by Max Planck. A hollow metallic sphere coated inside with platinum black with a fine hole acts as black body. Which is a perfect absorber and perfect radiator of energy.

→ The emission of radiation is due to vibrations of electrons in the body.

→ Radiation is associated with energy.

→ The energy is emitted or absorbed by a body discontinuously in the form of small packets called "Quantum".

→ Energy α υ          E = hυ

→ Propagation of radiant energy is in the form of quanta is called "quantization of energy".

E = n.hυ           (n = integer)

      Curves are obtained by plotting E against λ. As T increases, the peak of the curve shifts to lower λ. At a given T, the intensity of the radiant energy increases with the λ, reaches maximum and then decreases.
 

6. Explain the difference between emission spectra and absorption spectra.

A:

7.  Define atomic orbital. Explain the shapes of s, p and d orbitals with the help of diagrams.

A:  The three dimensional space around the nucleus of atom. Where the probability of finding an electron is maximum (95%) is called atomic orbital.

Shape of s Orbital: It is spherical in shape & has non directional property. Its l = 0

Shape of p Orbital: The shape of p orbital is dumb-bell and having 2 lobes. The lobes are oriented along X, Y, Z axes to give p_x, p_y, p_z orbitals.

Shape of d Orbital: The shape of d orbital is double dumb-bell and having 4 lobes. If the lobes are oriented along Z axis, gives d_z² orbital, oriented along X and Y axes, gives
d_x² - y² orbital, between 2 axes gives d_xy, d_yz and d_zx orbitals.