Question

how do you draw orbital diagrams

Answer 1

Orbital diagrams are pictorial representations of the electrons in an atom. In order to figure out where electrons go in an atom we have to follow 3 main rules.

1. Auf Bau principle: According to the Auf Bau Principle, each electron occupies the lowest energy orbital.

2. Pauli's exclusion principle: The Pauli Exclusion Principle says that only two electrons can fit into an single orbital.

3. Hund's rule: Hund's rule states that electrons go into different orbitals in the same sub-level before doubling up inside orbitals.

The first one being the Auf Bau Principle, the Auf Bau Principle states that each electron occupies the lowest energy orbital available. So let's look at the Auf Bau diagram which actually shows the order of filling the electrons from lowest to higher energy levels.

The second rule that we're going to talk about is the Pauli Exclusion Principle which basically states that there are maximum 2 electrons per orbital. So an orbital can only hold 2 electrons and that's it no more. It can hold 1 but it cannot hold more than 2.

Lastly the Hund's Rule states that they must occupy all orbitals of equal in energy before pairing up. So just like electron are both negative they're all negatively charged they're not going want to be really close to each other, so they're in equal energy they're going to occupy all the energy levels of that same energy first before they pair up because they typically don't like being really close to each other.

Ex: Fe-26 Iron we know is on its ground state of 26 electrons, so we know the first electrons are going to go into the 1s orbital and we said 2 electrons can fall into the 1s orbital. After the 1s orbital is a 2s, 2 electrons are going to go in there as well, then you have the 2p and don't forget the p sublevels has 3 orbitals so we're going to draw 3 dashes indicating the 3p sublevel and the electrons are going to go in all of them first before pairing up so right now we have a total of 10 electrons this is a 2p sublevel. After the 2p sublevel we're going to go into the 3s, 2 electrons are going to fall into there making 12 after 3s we're going to go into the 3p, we're gong to draw 3 dashes 1, 2, 3, 4, 5, 6, so 12, 14, 16, 18 electrons. After the 3p we're going to go into the 4s no we're not going to go into the 3d we go right into the 4s which is 1, so you have 2 electrons there, so you have 2, 4, 6, 8, 10, 12, 14, 16, 18, 20, we have 6 electrons left. The next one is a d, d is a 5 orbitals all the same energies we're going to draw 5 dashes 2, 3, 4, 5, all are the 3d, so we're going to draw I need 6 more so 1, 2, 3, 4, 5, 6 and this is how you draw orbital diagrams.