Valence-Shell Configurations

[Jake Ney lecture 1 discussion 1F]

Problem 2.55 asks to give the notion for valence shell configurations for entire groups such as the Alkali Earth metals. Can someone please explain how to determine the valence shell configurations for different groups and how these configurations relate to electron configurations?

[Emma Gillette 3J]

Because groups go down the periodic table and the table is organized by properties (including electron shell configuration), each group has similar valence shell configurations with different principle quantum numbers (period numbers). For example, the alkali metals all have one valence electron filling the s orbital, so the alkali metals have a valence electron notation of ns^1 with n being the period number. The valence electron configuration only includes the outermost electrons, so the previous electrons aren't included in the configuration (Ex: Potassium's valence shell configuration is 4s^1, but the whole electron configuration is [Ar] 4s^1).

[Victor Qiu 1C]

Valence shell configuration refers to the electrons in the outermost shell. The alkali earth metals are beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra), and the respective electron configurations are [He] 2s², [Ne] 3s², [Ar] 4s², [Kr] 5s², [Xe] 6s². Therefore, the valence shell configuration are 2s², 3s², 4s², 5s², 6s², respectively.