What element has 7 valence electrons on it's 5th energy level?

Chlorine has 7 valence shell electrons, 2 in the 3s orbital and 5 in the 3p orbital. Since a full shell of valence electrons (8) is the most stable configuration, chlorine tends not to lose electrons but to gain one electron to fill the final 3p orbital and give it 8 valence electrons like its neighboring noble gas argon

Explanation:

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