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 px, py, pz 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 dz2 orbital, oriented along X and Y axes, gives
dx2 - y2 orbital, between 2 axes gives dxy, dyz and dzx orbitals.