Synthetic element
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The chemical elements labeled as "synthetic" are unstable, with a half-life so short (ranging from a fraction of millisecond to a few million years) relative to the age of the Earth that any atoms of that element that may have been present when the Earth formed have long since completely decayed away. Hence they are only known on Earth as the product of nuclear reactors or particle accelerators.
The first synthetic element created was technetium, which filled a gap in the periodic table, and the discovery that there were no stable isotopes of technetium explained its absence on Earth: its 4.2 million year half-life meant that none remained from the time of formation of the Earth.
Synthetic elements include:
- Americium symbol Am, atomic number 95
- Berkelium symbol Bk, atomic number 97
- Bohrium symbol Bh, atomic number 107
- Curium symbol Cm, atomic number 96
- Californium symbol Cf, atomic number 98
- Dubnium symbol Db, atomic number 105
- Einsteinium symbol Es, atomic number 99
- Fermium symbol Fm, atomic number 100
- Hassium symbol Hs, atomic number 108
- Lawrencium symbol Lr, atomic number 103
- Mendelevium symbol Md, atomic number 101
- Meitnerium symbol Mt, atomic number 109
- Neptunium symbol Np, atomic number 93
- Nobelium symbol No, atomic number 102
- Rutherfordium symbol Rf, atomic number 104
- Seaborgium symbol Sg, atomic number 106
- Darmstadtium symbol Ds, atomic number 110
- Roentgenium symbol Rg, atomic number 111
Provisional names for recently observed synthetic elements:
ca:Element sintètic es:Elemento sintético fr:Élément synthétique gl:Elemento sintético ko:인공 원소 pt:Elemento sintético ru:Синтезированные химические элементы th:ธาตุสังเคราะห์ zh:人工合成元素