The Electron Configuration: Condensed: Videos & Practice Problems

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

Condensed electron configuration is an efficient method for representing the arrangement of electrons in an atom or ion. This approach simplifies the process by starting with the last noble gas preceding the element in question. Understanding the periodic table is crucial, as it is divided into blocks: the s block begins with 1s, followed by the p block, d block, and f block. When tasked with finding the electron configuration, it is essential to identify the specific element and the noble gas that comes before it. Unless specified otherwise, it is generally assumed that the condensed method is preferred over the full ground state electron configuration. This technique not only streamlines the writing of electron configurations but also aids in visualizing the electron distribution across different energy levels.

Condensed Electron Configuration Example

To determine the condensed electron configuration for an aluminum atom, which is neutral and has an atomic number of 13, we follow a systematic approach. First, we identify aluminum on the periodic table, noting that its atomic number indicates it has 13 electrons.

The next step involves locating the nearest noble gas that precedes aluminum in the periodic table. In this case, the noble gas is neon, which has an electron configuration of [Ne]. We place this noble gas in brackets to represent the core electrons.

After establishing the noble gas core, we continue to fill in the remaining electrons for aluminum. Following neon, we add the electrons in the 3s and 3p orbitals. Specifically, we have two electrons in the 3s subshell and one electron in the 3p subshell. Therefore, the complete condensed electron configuration for aluminum is:

[Ne] 3s2 3p1.

This condensed notation simplifies the representation of electron arrangements, allowing us to avoid writing out the full configuration of 1s2 2s2 2p6 3s2 3p1. By using the condensed form, we save time and streamline the process of writing electron configurations 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.