The Electron Configuration: Condensed: Study with Video Lessons, Practice Problems & Examples

Condensed electron configurations provide a shorthand method for representing the electron arrangements of elements or ions by starting with the last noble gas preceding the element in question. This approach simplifies the process of writing out full electron configurations, which can be lengthy for elements with many electrons. By identifying the noble gas closest to the element on the periodic table, students can quickly determine the remaining electron configuration. This technique is commonly used unless specifically instructed to provide a full ground state electron configuration. Understanding and utilizing condensed electron configurations is essential for efficiently tackling questions related to electron arrangements in chemistry.

Condensed Electron Configuration

We're going to say here that the condensed electron configuration is a faster way to write out electron arrangements for elements or ions. We're going to say with condensed electron configurations, we start at the last noble gas before the desired element. And if we take a look here, remember this is our reimagining of the periodic table.

We have our S block where it begins with 1S. We have our P block here. We have our d block here, and we have our F block down here with the condensed electron configuration. It's important to know which element are we being asked to find the electron configuration of and what's the noble gas before it.

We're going to say moving forward, this will be the primary method to write electron configuration because it's the faster, easier way to do it. Unless they say full ground state electron configuration, we usually just assume that this is the method they want us to write the electron configuration.

So now that we know what the condensed electron configuration is, click on the next video and let's get to work on an example question.

Condensed Electron Configuration Example

Here it says to provide the condensed electron configuration for the aluminum atom. Atom means that we're dealing with the neutral form of it if you look on the periodic table. So step one, we have to find the element on the periodic table. So aluminum has an atomic number of 13, which means it has 13 electrons involved.

Step 2. We're going to locate the noble gas that comes before the element and place it inside brackets. So the noble gas before aluminum is neon, so put it in brackets. TE 3 continuing from the noble gas in brackets, complete the rest of the electron configuration. So we've dealt with neon. So let's continue onward to aluminum. So next would come 3 S2 and then 3P1.

So this would be the condensed electron configuration of aluminum. Instead of having to write 1S22S22P63S23P1 we have this new condensed electron configuration. Neon here is taking the spot of all of this, so it's easier and faster for us to write the electron configuration of aluminum in this regard. So just remember the condensed electron configuration saves us a lot of time in terms of writing out the electron arrangements for elements and ions.

Write the condensed electron configuration and electron orbital diagram for the following element: Zinc 

• A. [Ar] 4s² 3d⁹
• B. [Kr] 4s² 3d¹⁰
• C. [Ar] 4s² 3d¹⁰
• D. [Ar] 4s¹ 3d¹⁰

Answer: (C)

Here’s what students ask on this topic:

What is the condensed electron configuration?

A condensed electron configuration is a shorthand representation of an element's electron configuration that simplifies the full electron configuration by denoting the core electrons with the noble gas that precedes the element in the periodic table. The noble gas symbol is placed in brackets, and it represents all the electron configurations up to that noble gas. After the noble gas symbol, you write the electron configuration for the outer (valence) electrons, which are responsible for the chemical properties of the element.

For example, the full electron configuration for iron (Fe), which has 26 electrons, is:

${\mathrm{1s}}^2{\mathrm{2s}}^2{\mathrm{2p}}^6{\mathrm{3s}}^2{\mathrm{3p}}^6{\mathrm{3d}}^6{\mathrm{4s}}^2$

The condensed electron configuration for iron starts with the noble gas that comes before it in the periodic table, which is argon (Ar), and then it includes the configuration from the 3d and 4s subshells:

$\left[\mathrm{Ar}\right]{\mathrm{3d}}^6{\mathrm{4s}}^2$

This shows the configuration of the electrons that are not in the core represented by argon, which makes it easier to understand and work with, especially for elements with a large number of electrons.

How do you write condensed electron configuration?

Writing a condensed electron configuration involves using the electron configuration of the nearest noble gas as a starting point to represent the inner-shell electrons, followed by the configuration of the outer-shell electrons. Here's how you can write it:

1. Identify the nearest noble gas that comes before your element in the periodic table. For example, if you're writing the configuration for chlorine (Cl), the nearest noble gas before it is neon (Ne).
2. Write the symbol of the noble gas in square brackets to represent all the electron configurations up to that noble gas. For chlorine, you would start with [Ne].
3. Continue with the electron configuration for the remaining electrons beyond the noble gas configuration. Chlorine has 7 more electrons past neon, so you would add ${\mathrm{3s}}^2{\mathrm{3p}}^{5}to\; represent\; these\; electrons.$
4. Combine the noble gas notation with the additional electron configuration. For chlorine, the condensed electron configuration would be [Ne]3s2 3p5.

Remember, this method only details the valence electrons, which are the electrons in the outermost shell that are added after the noble gas configuration.