The Electron Configuration: Condensed: Videos & Practice Problems

Condensed electron configuration is a streamlined method for representing electron arrangements in elements or ions. It begins with the last noble gas preceding the element in question, simplifying the notation. This approach is favored for its efficiency, especially when full ground state configurations are not required. Understanding the periodic table's structure, including the s, p, d, and f blocks, is essential for determining the correct noble gas reference. Mastery of this method is crucial for students studying atomic structure and electron configurations.

The Electron Configuration: Condensed

Condensed electron configuration is an efficient method for representing the electron arrangements of elements and ions. This approach begins with the last noble gas preceding the element in question, allowing for a simplified notation that highlights only the valence electrons beyond the noble gas core.

To construct a condensed electron configuration, one must first identify the element and locate the nearest noble gas on the periodic table. The periodic table is organized into blocks: the s block starts with 1s, followed by the p block, d block, and f block. This organization is crucial for determining the order in which electrons fill the atomic orbitals according to the Aufbau principle.

For most scenarios, unless specifically instructed to provide the full ground state electron configuration, the condensed method is preferred due to its speed and simplicity. This method streamlines the process of writing electron configurations, making it the primary approach in many educational contexts.

The Electron Configuration: Condensed Example 1

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 (Ne), which has an electron configuration of 1s^2 2s^2 2p^6. We represent this noble gas configuration in brackets: [Ne].

After placing the noble gas configuration in brackets, we continue to fill in the remaining electrons for aluminum. Following neon, we add the electrons in the 3s and 3p orbitals. Thus, the next part of the configuration is 3s^2 3p^1.

Combining these components, the complete condensed electron configuration for aluminum is:

[Ne] 3s^2 3p^1.

This condensed form is significantly more efficient than writing out the full electron configuration, which would be 1s^2 2s^2 2p^6 3s^2 3p^1. Using the condensed configuration not only saves time but also simplifies the representation of electron arrangements for elements and ions.

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

To determine the condensed electron configuration and electron orbital diagram for zinc, we start by noting that zinc has an atomic number of 30, indicating it has 30 electrons. The noble gas preceding zinc on the periodic table is argon, which accounts for the first 18 electrons. Therefore, the condensed electron configuration for zinc can be expressed as:

[Ar] 4s² 3d¹⁰

In this configuration, [Ar] represents the electron configuration of argon, while 4s² indicates that there are 2 electrons in the 4s sublevel, and 3d¹⁰ signifies that all 10 electrons fill the 3d sublevel.

For the electron orbital diagram, we begin with the noble gas notation, which encompasses all electrons from 1s² to 3p⁶. The s sublevel contains 1 orbital, while the d sublevel consists of 5 orbitals. According to Hund's rule, we first fill each of the five d orbitals with one electron (up spin) before pairing them (down spin). The orbital diagram for zinc can be illustrated as follows:

4s: ↑↓

3d: ↑↑↑↑↑

3d: ↓↓

This representation shows that the 4s sublevel is fully occupied with 2 electrons, while the 3d sublevel is also fully occupied with 10 electrons, following the appropriate filling order and Hund's rule.

Here’s what students ask on this topic:

What is the condensed electron configuration of iron (Fe)?

The condensed electron configuration of iron (Fe) starts with the noble gas preceding it, which is argon (Ar). Iron has an atomic number of 26. The configuration is written as [Ar] 3d⁶ 4s². This notation indicates that after the electron configuration of argon, iron has six electrons in the 3d subshell and two electrons in the 4s subshell.

How do you determine the noble gas to use in a condensed electron configuration?

To determine the noble gas to use in a condensed electron configuration, locate the element on the periodic table and identify the noble gas that comes immediately before it. Noble gases are found in Group 18 of the periodic table. For example, for an element like sulfur (S), which is in period 3, the preceding noble gas is neon (Ne). Therefore, the condensed electron configuration for sulfur would start with [Ne].

Why is the condensed electron configuration method preferred over the full ground state configuration?

The condensed electron configuration method is preferred because it simplifies the notation, making it quicker and easier to write. Instead of listing all the electron subshells from the beginning, it starts with the electron configuration of the last noble gas, which serves as a shorthand. This is particularly useful for elements with many electrons, as it reduces the complexity and length of the configuration.

What is the condensed electron configuration of the chloride ion (Cl^-)?

The chloride ion (Cl^-) has gained one electron compared to the neutral chlorine atom. Chlorine has an atomic number of 17, and its neutral condensed electron configuration is [Ne] 3s² 3p⁵. When it gains an electron to become Cl^-, the configuration becomes [Ne] 3s² 3p⁶, which is the same as the electron configuration of the noble gas argon (Ar).

How do you write the condensed electron configuration for transition metals?

To write the condensed electron configuration for transition metals, start with the noble gas preceding the element, then add the electrons in the 3d and 4s subshells. For example, for cobalt (Co), which has an atomic number of 27, the preceding noble gas is argon (Ar). The condensed electron configuration is [Ar] 3d⁷ 4s². Note that the 4s subshell is filled before the 3d subshell, but when writing the configuration, the 3d subshell is listed first.