can anyone plzz tel me the sequence of electron filling in orbitals

Dear Polisetti

Electrons fill orbitals starting at the lowest available (possible) energy states before filling higher states (e.g. 1s before 2s). The number of electrons that can occupy each orbital is limited by the Pauli exclusion principle. If multiple orbitals of the same energy are available, Hund's rule states that unoccupied orbitals will be filled before occupied orbitals are reused (by electrons having different spins).

So orbitals with a lower n+l value are filled before those with higher n+l values. The rule is based on the total number of nodes in the atomic orbital, n+l, which is related to the energy.In the case of equal n+l values, the orbital with a lower n value is filled first.

All the best.

AKASH GOYAL

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The Aufbau principle states that in the ground state of an atom, an electron enters the orbital of lowest energy first, and then the subsequent electrons are fed in the order of increasing energies into the orbitals. The following sequence is observed for orbitals in the increasing energy:1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s.

Or you can understand by this diagram too.

Please do reply ffor this post.......if you like it......

thanks....

The Aufbau principle (from the German Aufbau meaning "building up, construction": also Aufbau rule or building-up principle) is used to determine the electron configuration an atom molecule or ion. The principle postulates a hypothetical process in which an atom is "built up" by progressively adding electrons. As they are added, they assume their most stable conditions with respect to the nucleus and those electrons already there.

According to the principle, electrons fill orbitals starting at the lowest available (possible) energy states before filling higher states (e.g. 1s before 2s). The number of electrons that can occupy each orbital is limited by the Pauli exclusion principle. If multiple orbitals of the same energy are available, Hund's rule states that unoccupied orbitals will be filled before occupied orbitals are reused (by electrons having different spins).

1s     

2s     2p

3s     3p      3d

4s     4p      4d      4f

5s     5p      5d      5f

6s     6p      6d

7s     7p