Salient Features of Aufbau Principle
Various features of the Aufbau Principle are,
- The energy of an orbital depends on the sum of the values of the principal quantum number (n) and the azimuthal sum number (I). This is called the (n + l) rule. According to this rule,
- In a neutral isolated atom, the lower the value of (n + l) for an orbital, the lower its energy. However, if two different types of orbitals have the same value (n + l), then the orbitals with a lower value of n have less energy.
|
Type of Orbital |
Value of n |
Value of l |
Value of n+l |
Relative Energy |
|---|---|---|---|---|
|
1s |
1 |
0 |
1+0 = 1 |
Lowest energy |
|
2s |
2 |
0 |
2+0 = 2 |
Higher energy than 1s orbital |
|
2p 3s |
2 3 |
1 0 |
2+1 = 3 3+0 = 3 |
2p orbitals(n=2) have lower energy than 3s(n=3) orbital. |
|
3p 4s |
3 4 |
1 0 |
3+1 = 4 4+0 = 4 |
3p orbitals(n=3) have lower energy than 4s(n=4) orbitals. |
|
3d 4p |
3 4 |
2 1 |
3+2 = 5 4+1 = 5 |
3d orbitals(n=3) have lower energy than 4p(n=4) orbitals. |
From the description given in the table, it follows that the energies of the various orbitals increase with the increase in the number of the principal quantum number.
- Thus the order in which the electrons are filled in the atomic orbital of the atom is, 1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, 5s, 4d, 5p, 6s, 4f, 5d, 6p, 7s, 5f, 6d, 7p…
Aufbau Principle
Aufbau Principle is the basic method that tells us how the electrons are filled in the atomic orbital. According to the Aufbau Principle, the filling of the electrons in the ground state of an atom follow a basic pattern. This principle tells us that the electrons in the atomic orbital of any atoms are filled in the ascending order of their energy and for finding the energy of the atomic orbital they follow the “n+l” rule.
Aufbau Principle
In this article, we will learn about Aufbau Principle, Features of the Aufbau Principle, its exceptions and limitations in detail.