If n = 6, the correct sequence for filling of electrons will be
- ns (n-2)f (n-1)d np
- ns (n-1)d (n-2)f np
- ns (n-2)f np (n-1)d
- ns np (n-1)d (n-2)f
Answer
(1) ns (n-2)f (n-1)d np
Solution
For n = 6 the subshells are 6s, 4f, 5d and 6p. By the (n + l) rule:
6s: 6 + 0 = 6; 4f: 4 + 3 = 7; 5d: 5 + 2 = 7; 6p: 6 + 1 = 7
for equal (n + l), the subshell with lower n is filled first
6s 4f 5d 6p
ns (n-2)f (n-1)d np
Answer: (1)