Editing Synthetic element (section)

==Properties==
All elements with atomic number greater than 94 decay quickly enough into lighter elements such that any [[atom]]s of these that may have existed when the Earth formed (about 4.6&nbsp;billion years ago) have long since decayed.<ref>{{cite web |last1=Redd |first1=Nola |title=How Was Earth Formed? |url=https://www.space.com/19175-how-was-earth-formed.html |website=Space.com |date=November 2016 |access-date=16 May 2019}}</ref><ref>{{cite web |title=Synthetic elements |url=https://www.infoplease.com/encyclopedia/science/chemistry/elements/synthetic-elements |website=Infoplease |access-date=16 May 2019}}</ref> Synthetic elements now present on Earth are the product of atomic bombs or experiments that involve [[nuclear reactor]]s or [[particle accelerator]]s, via [[nuclear fusion]] or [[neutron absorption]].<ref>{{cite web |last1=Kulkarni |first1=Mayuri |title=A Complete List of Man-made Synthetic Elements |url=https://sciencestruck.com/synthetic-elements |website=ScienceStuck |date=15 June 2009 |access-date=16 May 2019}}</ref>

[[Atomic mass]] for natural elements is based on weighted average abundance of natural [[isotope]]s in [[Earth]]'s [[crust (geology)|crust]] and [[atmosphere]]. For synthetic elements, there is no "natural isotope abundance". Therefore, for synthetic elements the total [[nucleon]] count ([[proton]]s plus [[neutron]]s) of the most stable [[isotope]], i.e., the isotope with the longest [[half-life]]—is listed in brackets as the atomic mass.