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

The element that has a complete valence electron shell is

Argon(Ar)

Argon is in group 18 and period three in the periodic table. Therefore Argon electronic configuration is 2.8.8 or 1s^2 2s^2 2P^6 3S^2 3P^6 or [Ne] 3s^2 3p^6. The valence electrons of Argon is 3s^2 3p^6 which are completely filled since an 3S subshell can hold a maximum of 3 electrons while a 3P subshell can accommodate a a maximum of 6 electrons hence, Argon has a complete filled valence shell.

the movement of aircraft through clouds can even cause lightning strikes. a single lightning event is a "flash", which is a complex, multi-stage explosively ejected.

explanation:

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oxygen, selenium, tellurium, and polonium.

they're all from the same group as sulfur (group 16).