Original: 15 5 |-style="background-color:#c0ffff" |Argon||Ar||18||39.948(1)The isotopic composition varies in terrestrial material such that a more precise atomic weight can not be given.
Simplified: 15 5 |- |Argon||Ar||18||39.948(1) The isotopic composition varies in terrestrial material such that a more precise atomic weight can not be given.