Electron Shell Chemistry Example 4

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Example 4

medium
Determine the electron shell arrangement for chlorine (Z=17Z = 17). How many electrons are in the outermost shell, and what does this predict about chlorine's chemical behavior?

Solution

  1. 1
    Chlorine has 17 electrons. Shell 1: 2, Shell 2: 8, Shell 3: 17−2−8=717 - 2 - 8 = 7.
  2. 2
    The outermost shell has 7 electrons, which is one short of a stable octet. Chlorine tends to gain one electron to form Cl−\text{Cl}^-, making it a highly reactive nonmetal.

Answer

Cl: 2, 8, 7 — tends to gain 1 electron\text{Cl: 2, 8, 7 — tends to gain 1 electron}
Elements with nearly full outer shells tend to gain electrons to complete the octet. This is why chlorine is a strong oxidizing agent and readily forms ionic bonds with metals.

About Electron Shell

A discrete energy level surrounding the atomic nucleus where electrons reside, with each shell (n=1,2,3,...n = 1, 2, 3, ...) holding a maximum of 2n22n^2.

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