Question

Aufbau principle fails to explain the configuration of element with atomic number (< 29)

Answer 1

Answer:

Chromium has atomic number 24.

Actual electronic configuration: 1s

2

2s

2

2p

6

3s

2

3p

6

3d

85

4s

1

.

According to Aufbau: 1s

2

2s

2

2p

6

3s

2

3p

6

3d

4

4s

2

.

Discripency is because of extra stability of half filled (d5) orbitals.