What is the order in which electrons start filling the orbitals? a: 1s 2s 2p 3s 3p 4s 3d 4p b: 1s 2s 2p 3s 3p 3d 4s 4p c: 1s 2s 2p 3s 4s 3p 3d 4p d: 1s 2s 2p 3s 4s 4p 3p 3d e: 1s 2s 2p 3s 4s 3p 4p 3d

The answer is actually A, 1s 2s 2p 3s 3p 4s 3d 4p.

The correct answer is option A, that is, 1s 2s 2p 3s 3p 4s 3d 4p.

Explanation:

In quantum chemistry and atomic physics, the distribution of electrons of a molecule or an atom in atomic or molecular orbitals is known as the electronic configuration. The electronic configurations illustrate each electron as moving autonomously in an orbital. Mathematically, the configurations are illustrated by configuration state functions or Slater determinants. The electron starts filling the orbitals in an order 1s 2s 2p 3s 3p 4s 3d 4p 5s 4d 5p 6s 4f 5d 7s 5f 6d and 7p.

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