The chemical elements labelled 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. A chemical element, often called simply element, is the class of atoms which contain the same number of protons. ... Half-Life For a quantity subject to exponential decay, the half-life is the time required for the quantity to fall to half of its initial value. ... Earth, also known as the Earth, Terra, and (mostly in the 19th century) Tellus, is the third-closest planet to the Sun. ... Properties For alternative meanings see atom (disambiguation). ... Nuclear power station at Leibstadt, Switzerland. ... One of the early particle accelerators responsible for development of the atomic bomb. ...

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. General Name, Symbol, Number technetium, Tc, 43 Chemical series transition metals Group, Period, Block 7, 5, d Appearance silvery gray metal Atomic mass (98) g/mol Electron configuration [Kr] 4d5 5s2 Electrons per shell 2, 8, 18, 13, 2 Physical properties Phase solid Density (near r. ... The periodic table of the chemical elements, also called the Mendeleev periodic table, is a tabular display of the known chemical elements. ... Different isotopes of one chemical element may have different radioactive properties. ... (Redirected from 1e14 s) To help compare orders of magnitude of different times this page lists times between 3. ...

Synthetic elements include:

• Americium
• Berkelium
• Bohrium
• Curium
• Californium
• Dubnium
• Einsteinium
• Fermium
• Hassium
• Lawrencium
• Mendelevium
• Meitnerium
• Neptunium
• Nobelium
• Rutherfordium
• Seaborgium
• Darmstadtium
• Roentgenium

Provisional names for recently observed synthetic elements: General Name, Symbol, Number americium, Am, 95 Chemical series actinides Group, Period, Block ?, 7, f Appearance silvery white Atomic mass (243) g/mol Electron configuration [Rn] 5f7 7s2 Electrons per shell 2, 8, 18, 32, 25, 8, 2 Physical properties Phase solid Density (near r. ... Known properties Name, Symbol, Number Berkelium, Bk, 97 Chemical series Actinides Period, Block 7, f Appearance unknown; probably metallic, silvery white or gray Atomic weight [247] amu Electron configuration [Rn] 5f9 7s2 e- s per energy level 2,8,18,32,27,8,2 State of matter solid Density 14780... General Name, Symbol, Number bohrium, Bh, 107 Chemical series transition metals Group, Period, Block 7, 7, d Appearance unknown, probably silvery white or metallic gray Atomic mass (264) g/mol Electron configuration perhaps [Rn] 5f14 6d5 7s2 (guess based on rhenium) Electrons per shell 2, 8, 18, 32, 32, 13... General Name, Symbol, Number curium, Cm, 96 Chemical series actinides Group, Period, Block ?, 7, f Appearance silvery Atomic mass (247) g/mol Electron configuration [Rn] 5f7 6d1 7s2 Electrons per shell 2, 8, 18, 32, 25, 9, 2 Physical properties Phase solid Density (near r. ... General Name, Symbol, Number californium, Cf, 98 Chemical series actinides Group, Period, Block ?, 7, f Appearance unknown, probably silvery white or metallic gray Atomic mass (251) g/mol Electron configuration [Rn] 5f10 7s2 Electrons per shell 2, 8, 18, 32, 28, 8, 2 Physical properties Phase solid Density (near r. ... General Name, Symbol, Number dubnium, Db, 105 Chemical series transition metals Group, Period, Block 5, 7, d Appearance unknown, probably silvery white or metallic gray Atomic mass (262) g/mol Electron configuration perhaps [Rn] 5f14 6d3 7s2 (guess based on tantalum) Electrons per shell 2, 8, 18, 32, 32, 11... General Name, Symbol, Number einsteinium, Es, 99 Chemical series actinides Group, Period, Block ?, 7, f Appearance unknown, probably silvery white or metallic gray Atomic mass (252) g/mol Electron configuration [Rn] 5f11 7s2 Electrons per shell 2, 8, 18, 32, 29, 8, 2 Physical properties Phase solid Density (near r. ... General Name, Symbol, Number fermium, Fm, 100 Chemical series actinides Group, Period, Block ?, 7, f Appearance unknown, probably silvery white or metallic gray Atomic mass (257) g/mol Electron configuration [Rn] 5f12 7s2 Electrons per shell 2, 8, 18, 32, 30, 8, 2 Physical properties Phase solid Melting point 1800... General Name, Symbol, Number hassium, Hs, 108 Chemical series transition metals Group, Period, Block 8, 7, d Appearance unknown, probably silvery white or metallic gray Atomic mass (269) g/mol Electron configuration perhaps [Rn] 5f14 6d6 7s2 (guess based on osmium) Electrons per shell 2, 8, 18, 32, 32, 14... General Name, Symbol, Number lawrencium, Lr, 103 Chemical series actinides Group, Period, Block 3, 7, d Appearance unknown, probably silvery white or metallic gray Atomic mass (262) g/mol Electron configuration probably [Rn] 5f14 7s2 7p1 Electrons per shell 2, 8, 18, 32, 32, 8, 3 Phase presumably a solid... General Name, Symbol, Number mendelevium, Md, 101 Chemical series actinides Group, Period, Block ?, 7, f Appearance unknown, probably silvery white or metallic gray Atomic mass (258) g/mol Electron configuration [Rn] 5f13 7s2 Electrons per shell 2, 8, 18, 32, 31, 8, 2 Physical properties Phase solid Melting point 1100... Known properties Name, Symbol, Number meitnerium, 109, Mt Chemical series Transition metals Group, Period, Block 9, 7, d Appearance unknown Atomic weight [268] amu Electron configuration probably [Rn] 5f14 6d7 7s2 e- s per energy level 2, 8, 18, 32, 32, 15, 2 State of matter Presumably a solid Meitnerium... General Name, Symbol, Number neptunium, Np, 93 Chemical series actinides Group, Period, Block ?, 7, f Appearance silvery metallic Atomic mass (237) g/mol Electron configuration [Rn] 5f4 6d1 7s2 Electrons per shell 2, 8, 18, 32, 22, 9, 2 Physical properties Phase solid Density (near r. ... Known properties Name, Symbol, Number Nobelium, No, 102 Chemical series Actinides Period, Block 7, f Appearance unknown Atomic weight [259] u Electron configuration [Rn] 5f14 7s2 e- s per energy level 2, 8, 18, 32, 32, 8, 2 State of matter Presumably a solid Most stable isotopes Nobelium, also known... General Name, Symbol, Number rutherfordium, Rf, 104 Chemical series transition metals Group, Period, Block 4, 7, d Appearance unknown, probably silvery white or metallic gray Atomic mass (261) g/mol Electron configuration probably [Rn] 5f14 6d2 7s2 Electrons per shell 2, 8, 18, 32, 32, 10, 2 Phase presumably a... Known properties Name, Symbol, Number seaborgium, Sg, 106 Chemical series Transition metals Group, Period, Block 6, 7 , d Appearance unknown Atomic weight [266] amu Electron configuration probably [Rn]5f14 6d4 7s2 e- s per energy level 2, 8, 18, 32, 32, 12, 2 State of matter presumably a solid Seaborgium... Known properties Name, Symbol, Number Darmstadtium, Ds, 110 Chemical series Transition metals Group, Period, Block 10, 7, d Appearance unknown Atomic weight From [267] amu to [281] amu Electron configuration probably [Rn] 5f14 6d9 7s1 a guess based upon platinum e- s per energy level 2, 8, 18, 32, 32... General Name, Symbol, Number roentgenium, Rg, 111 Chemical series transition metals Group, Period, Block 11, 7, d Appearance unknown, probably silvery white or metallic gray Atomic mass (272) g/mol Electron configuration perhaps [Rn] 5f14 6d10 7s1 (guess based on gold) Electrons per shell 2, 8, 18, 32, 32, 18...

• Ununhexium
• Ununpentium
• Ununtrium