Order of Orbitals

[veneziaramirez 3I]

Does the order of orbitals matter? For instance is it okay if we either write 4s2 3d10 or 3d10 4s2?

[Thuy-Anh Bui 1I]

The order of orbitals does matter. When you write the electron configuration for an element, you must follow the Aufbau ("building up") Principle and write the orbitals in order of increasing energy. Therefore, if you have 3d and 4s, you need to write 3d before 4s because the 3d state is lower in energy than 4s.

[Akshay Anand]

Usually it doesn't matter, but I know Professor Lavelle wants us to label it in order of increasing n (shell). So you should write it as 3d10 4s2 on all tests and midterms.

[Mikaila 3E]

It is also helpful to write it in the order of increasing n-values (shell) when writing the electron configurations for ions. The electrons in the highest energy level are the ones that get added to or removed, not the lower energy levels.

[isauramora3K]

Technically it isn't incorrect to write it in that order, but Dr. Lavelle prefers you put them in order of increasing energy. It makes writing electron configuration for ions easier because the last orbital is the one that loses or gains electrons first and it goes backwards from there.

[Pooja Nair 1C]

If you're wondering about the order in respect to the d orbital, once you reach Ar the next electron goes into the 4s subshell because it has a lower energy than the 3d subshell. However, once the 3d subshell starts filling (element 21) it drops in energy level, which is why it is written first, and also why elements with the last electrons in the 3d shell lose electrons from the 4s shell first.

[William Cryer 1L]

the easiest way I've found to write electron configurations is just go in order from left to right on the periodic table, starting at 1s1 and making your way across and down the periodic table. As long as you know the p and d blocks, this makes it super easy!

[Yeyang Zu 2J]

Yes, it matters. You need to follow the Aufbau Principle, and write the orbitals from lowest energy to highest energy.

[Kailie_Giebink_1E]

im still confused as to when to use d versus s. I thought I got it but I don't

[Chem_Mod]

What do you mean by you aren't sure when to use d versus s? There are specific blocks of the periodic table, if that helps clarify things.
See this image: https://commons.wikimedia.org/wiki/File ... able_2.svg

[Isabella Barkett 1G]

The orbitals are differentiated in terms of their relative energy, s having the lowest and f having the highest (s<p<d<f).