The arrangement of orbitals on the basis of energy is based upon their (n +l) value. Lower the value of (n +l), lower is the energy . For orbitals having same value of (n +l), the orbital with lower value of n will have lower energy. I. Based upon the above information, arrange the following orbitals in the increasing order of energy (a) 1s, 2s, 3s, 2p (b) 4s, 3s, 3p, 4d (c) 5p, 4d, 5d, 4f, 6s (d) 5f, 6d, 7s, 7p II. Based upon the above information, solve the questions given below: (a) Which of the orbital out of 4d, 4f, 5s, 5p has the lowest energy ? (b) Which of the orbital out of 5p, 5d, 5f, 6s, 6p has the highest energy ?

The arrangement of orbitals on the basis of energy is based upon their

1.	The arrangement of orbitals on the basis of energy is based upon their (n +l) value. Lower the value of (n +l), lower is the energy . For orbitals having same value of (n +l), the orbital with lower value of n will have lower energy. I. Based upon the above information, arrange the following orbitals in the increasing order of energy (a) 1s, 2s, 3s, 2p (b) 4s, 3s, 3p, 4d (c) 5p, 4d, 5d, 4f, 6s (d) 5f, 6d, 7s, 7p II. Based upon the above information, solve the questions given below: (a) Which of the orbital out of 4d, 4f, 5s, 5p has the lowest energy ? (b) Which of the orbital out of 5p, 5d, 5f, 6s, 6p has the highest energy ?
Answer» Solution :I (a) `(n +L)` values are `2s =1 +0 =1, 2s = 2 + 0= 2, 3s = 3 + 0 = 3, 2p = 2 + 1 = 3` Hence, increasing order of their energy is `1s lt 2s lt 2p lt 3s`. (B) `4s = 4 + 0 = 4, 3s = 3 + 0 = 3, 3p = 3 +1 = 4, 4d = 4 + 2 = 6` Hence, `3s lt 3p lt 4s lt 4d` (c) `5p = 5 +1 = 6, 4d = 4 + 2 = 6, 5d= 5 + 2 = 7, 4f = 4 + 3 = 7, 6s = 6 + 0 = 6` Hence, `4d lt 5p lt 6s lt 4f lt 5d` (d) `5f = 5 + 3 = 8, 6d = 6 + 2 = 8, 7s = 7 + 0= 7, 7p = 7 + 1 = 8`. Hence, `7s lt 5f l 6d lt 7p` II. (a) `4d = 4 + 2 = 6, 4f = 4 + 3 = 7, 5s = 5 + 0 = 5, 7p = 7 + 1 = 8`. Hence, 5s has the lowest energy. (b) `5p = 5 + 1 =6, 5d = 5 + 2 = 7, 5f = 5 + 3 = 8, 6s = 6 + 0 = 6, 6P = 6 + 1 = 7` Hence, 5f has highest energy.