Original: 15 5 | - style = "background-color: #c 0ffff" | 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.