Heavy Elements  

Number Names when Chemically like (bold if verified)
92 Uranium (U) natural IIIa Neodymium
93 Neptunium (Np) natural IIIa Promethium
94 Plutonium (Pu) 1940 IIIa Samarium
95 Americium (Am) 1944 IIIa Europium
96 Curium (Cm) 1944 IIIa Gadolinium
97 Berkelium (Bk) 1949 IIIa Terbium
98 Californium (Cf) 1950 IIIa Dysprosium
99 Einsteinium (Es) 1952 IIIa Holmium
100 Fermium (Fm) 1953 IIIa Erbium
101 Mendelevium (Md) 1955 IIIa Thulium
102 Nobelium (No) 1958 IIIa Ytterbium
103 Lawrencium (Lr) 1961 IIIa Lutetium (and Yttrium, Scandium by some charts)
104 Unnilquadium (Unq)
Dubnium (Db)
Rutherfordium (Rf)
1964 4 IVa Hafnium, Zirconium, Titanium
105 Unnilpentium (Unp)
Joliotium (Jl)
Hahnium (Ha)
Dubnium (Db)
1968 5 Va Tantalum, Niobium, Vanadium
106 Unnilhexium (Unh)
Rutherfordium (Rf)
Seaborgium (Sg)
1974 6 VIa Tungsten, Molybdenum, Chromium
107 Unnilseptium (Uns)
Nielsbohrium (Ns)
Bohrium (Bh)
1981 7 VIIa Rhenium, Technitium, Manganese
108 Unniloctium
Hahnium (Ha or Hn)
Hassium (Hs)
1984 8 VIIIa Osmium, Ruthenium, Iron
109 Meitnerium (Mt)
Unnilennium (Une)
1982 9 VIIIa Iridium, Rhodium, Cobalt
110 Darmstadtium (Ds)
Ununnilium (Uun)
1994 10 VIIIa Platinum, Palladium, Nickel
111 Roentgenium (Rg)
Unununium (Uuu)
1994 11 Ib Gold, Silver, Copper
112 Ununbium (Uub) 1996 12 IIb Mercury, Cadmium, Zinc
113 Ununtertium (Uut) 13 IIIb Thallium, Indium, Gallium, Aluminum, Boron
114 Ununquadium (Uuq) 1998 14 IVb Lead, Tin, Germanium, Silicon, Carbon
115 Ununpentium (Uup) 15 Vb Bismuth, Antimony, Arsenic, Phosphorus, Nitrogen
116 Ununhexium (Uuh) 1999 16 VIb Polonium, Tellurium, Selenium, Sulfur, Oxygen
117 Ununseptium (Uus) 17 VIIb Astatine, Iodine, Bromine, Chlorine, Fluorine
118 Ununoctium (Uuo) 1999 18 VIIIb Radon, Xenon, Krypton, Argon, Neon, Helium

Ambiguous Names

Yes, the same names appear more than once in many cases. Elements were produced by different teams of scientists over the years, from different countries, and different names were suggested. It has been hard to form a consensus. For a while, the cold war played a role in perpetuating the disagreements. I found these names here:





Natural Occurrence of Transuranic Elements

At some point you probably "learned" that Uranium, element number 92, is the highest element on the periodic table that occurs in nature. Not true — neptunium and plutonium occur naturally. They are found in trace quantities in uranium ore. The neptunium is created when a neutron given off by a U-238 nucleus hits another uranium nucleus creating U-239, which then beta-decays to Np-239. The half-life of Np-239 is about 2 days, it then beta-decays into Pu-239. Thus, wherever U-238 occurs in sufficient concentrations, Np-239 and Pu-239 also occur, and if you consider the first to be a natural element then the others must be too. (U-238 is naturally occurring because the universe isn't old enough yet.)

Due to similar effects, it is even possible that a stray atoms of even heavier elements (such as americium) are created from time to time, only to decay again before anyone can detect them. Also, of course, there are scads of heavy isotopes that occur naturally during supernova explosions, only to disappear milliseconds later.

If you use "non-radioactive isotope" as the definition of a naturally-occurring isotope, then Uranium does not count as a naturally occurring element because all of its isotopes decay. (The most stable isotope is U-238 with a half life of 4 billion years. Uranium occurs in nature because its half-life is so long.)

"Magic Island" at Element 114

In the early 1960's it was thought that the "shell effects" that cause the neuclei He-4, O-16, Ca-40, Ca-48 and Pb-208 to be so stable, would also occur for Uuq-298 (which at the time was called simply element 114). It was even thought that isotopes near Uuq-298 might be stable enough to not decay at all. By the early 1980's it was established that there are no stable isotopes near Uuq-298 and that the heavy elements are difficult to produce.

However, a lighter isotope of element 112 has been shown to have a half-life of about 5 minutes (see this page). It has even been verified to have "adsorption" properties, like Mercury.

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