Question

Rank the following orbitals in terms of their energies.

7p,7s,5f,6p,6d,5d

Answer 1

Ans :- The correct decreasing order (i.e. higher to lower) of the following orbital is :

7p > 6d > 5f > 7s > 6p > 5d

Explanation :-

(n+l) Rule :-

The orbital having smaller value of (n+l) will have less energy than other orbital. if the two orbitals have same (n+l) values, then compare their n values, that is smaller n value orbital will have less energy than other orbital.

here, n = Prinicipal quantum number

l = Azimuthal orbital quantum number

For l = 0 (s-orbital)

l = 1 ( p-orbital)

l = 2 ( d-orbital) and

l = 3 ( f- orbital )

(a).7p

here, n = 7 and l = 1

so

n + l = 7+1 = 8

(b). 7s

here, n = 7 and l = 0

so

n + l = 7+0 = 7

(c).5f

here, n = 5 and l = 3

so

n + l = 5+3 = 8

(d).6p

here, n = 6 and l = 1

so

n + l = 6+1 = 7

(e).6d

here, n = 6 and l = 2

so

n + l = 6+2 = 8

(f).5d

here, n = 5 and l = 2

so

n + l = 5+2 = 7