Question

which element has a complete valence electron shell?
selenium (se)
oxygen (o)
fluorine (f)
argon (ar)

Explanation:

• Selenium (Se) has 6 valence electrons.
• Oxygen (O) has 6 valence electrons.
• Fluorine (F) has 7 valence electrons.
• Argon (Ar) is a noble gas. Noble gases have a complete valence electron shell (8 electrons for most noble gases, 2 for helium).

Answer:

argon (Ar)