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Example · Example 2

Q.Write the general outer electronic configuration of the Group 2 (alkaline earth metal) elements and name all six elements of the group.

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✓ Free question

Group 2 elements are called the alkaline earth metals. Each atom has the configuration of the preceding noble gas plus two electrons filling the outermost ss orbital, giving the general form [noble gas] ns2[\text{noble gas}]\,ns^2.

Writing this out for each member:

  • Beryllium (Z=4Z=4): [He] 2s2[\text{He}]\,2s^2
  • Magnesium (Z=12Z=12): [Ne] 3s2[\text{Ne}]\,3s^2
  • Calcium (Z=20Z=20): [Ar] 4s2[\text{Ar}]\,4s^2
  • Strontium (Z=38Z=38): [Kr] 5s2[\text{Kr}]\,5s^2
  • Barium (Z=56Z=56): [Xe] 6s2[\text{Xe}]\,6s^2
  • Radium (Z=88Z=88): [Rn] 7s2[\text{Rn}]\,7s^2

Losing both outer electrons gives the stable, noble-gas-configured M2+\text{M}^{2+} ion, so every member is characteristically divalent.

✓Final answer

The general outer configuration is ns2ns^2. The six elements are beryllium ([He]2s2[\text{He}]2s^2), magnesium ([Ne]3s2[\text{Ne}]3s^2), calcium ([Ar]4s2[\text{Ar}]4s^2), strontium ([Kr]5s2[\text{Kr}]5s^2), barium ([Xe]6s2[\text{Xe}]6s^2) and radium ([Rn]7s2[\text{Rn}]7s^2).

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