Short Hand

[Fdonovan 3D]

Would anyone mind explaining how the short hand for electron configurations works? For example Chromium, Cr: [Ar]3d⁵ 4s¹
How do you choose the element to base the shorthand off of?

[KHowe_1D]

You pick the noble gas before the element. Those are the ones on the far right of the periodic table. These are chosen because they have filled electron shells.

[KarineKim2L]

The element in the brackets [ ] is the noble gas from the group before the element you are creating the electron configuration for. This is shorthand because writing this noble gas(far right of periodic table) signifies the electron configuration up to that element. Then, you just have to write out the electron configuration for the most outer shell.

[Sanjana K - 2F]

So you want to base your shorthand off of the last element in the previous row (the last noble gas before your element). Chromium belongs in period 4 so you'd go to the previous row (period 3) and move to the last element (group 18), which is Argon.

The "s" block consists of groups 1-2, the "p" block of groups 13-18, and the "d" block of groups 3-12, and the "f" block of the inner transition metals. To go from argon to chromium, you have to go through 4s^2 and 3d^4, which is what you'd think to be the configuration of chromium. But chromium actually exists as [Ar] 3d^5 4s^1 because that's just the structure where the repulsion balance and the size of the energy gap between the 3d and 4s orbitals produces the lowest energy for the system (the most energetically stable state).

[simmoneokamoto3K]

ONce you get the base configuration, usually you don't want to have the long electron configuration, so we use the elements in the far-right column of the periodic table (starting with Helium and ending with Radon) for short-hand. Basically once you have the electron configuration, in the event that there are twelve electrons in an atom, you'll take the noble gas that has a electron number lower than that, in this case, Neon [Ne] which has ten electrons and subtract it from the initial number leaving you with five. So instead of your electron configuration being 1s^2 2s^2 2p^6 3s^2 3p^3, your electron configuration is [Ne]3s^2 3p^3. Hope this helps

[aishwarya_atmakuri]

You put the last noble gas configuration in brackets and then continue using spdf normally after that.

[Jasmine Vallarta 2L]

use the noble gas before the element you are writing the configuration for

[PranaviKolla2B]

Refer to the previous noble gas and put the name of that in brackets and then continue to write the configuration. Basically we just act as if the noble gas in the brackets acts as the configuration for the noble gas, so we would continue writing configuration as if we wrote the configuration up till that noble gas.

[Rhea Shah 2F]

Because the noble gases have their outer shell completely full, they are used in shorthand electron configurations. The noble gas of the period above that of the electron in focus is written in brackets, and then the valence electrons are written in after the brackets. This makes electron configurations easy to read and understand.

[Sreyes_1C]

since the configurations continue to get longer and longer, you can start the longer configurations with an abbreviation of the noble gas that comes before it. The noble gases are the column all the way to the right and they have full outer shells, which makes it possible for us to use them when doing the shorthand configurations.

[Marykate Abad 3L]

You can use the noble gas before it to substitute writing out the entire thing.

[Gabriel Ordonez 2K]

To write in short hand, find the specific element that you will use. Let’s use S for this example. Find the preceding noble gas first, which is in group 18 in the preceding period. In S’s case, it is Ne. You would write Ne in brackets first at the beginning of the configuration then finish it off normally with the spdf notation. So, for S, the noble gas configuration or short hand would be the following: [Ne]3s^2 3p^4.