Actinides
Thorium
a naturally occurring radioactive metal found at trace levels in soil, rocks, water, plants and animals
Rutherfordium
chemical element with the symbol Rf and atomic number 104
Cerium
a soft, ductile, and silvery-white metal that tarnishes when exposed to air
Polonium
a radioactive material that occurs naturally in the earth's crust at very low levels
Meitnerium
an artificially produced element belonging to the transuranium group, atomic number 109
Protactinium
a radioactive chemical element of the actinoid series of the periodic table
Tantalum
a shiny, silvery metal which is soft when is pure
Praseodymium
a component of didymium glass
Astatine
radioactive chemical element and the heaviest member of the halogen elements, or Group 17 (VIIa) of the periodic table
Darmstadtium
a chemical element with the symbol Ds and atomic number 110
Neptunium
a chemical element with the symbol Np and atomic number 93
Hassium
a synthetic chemical element, expected to have chemical properties similar to those of osmium and a silvery white or metallic gray colour.
Neodymium
one of the more reactive lanthanides
Bismuth
the most metallic and the least abundant of the elements in the nitrogen group
Roentgenium
a chemical element with the symbol Rg and atomic number 111
Americium
a synthetic radioactive chemical element with the symbol Am and atomic number 95
Osmium
one of the platinum metals of Groups 8–10 (VIIIb), Periods 5 and 6, of the periodic table and the densest naturally occurring element
Samarium
a chemical element with symbol Sm and atomic number 62
Thallium
a soft, heavy, inelastic metal
Copernicium
a man-made element of which only a few atoms have ever been made
Curium
a transuranic, radioactive chemical element with the symbol Cm and atomic number 96
Rhenium
a chemical element with the symbol Re and atomic number 75
Gadolinium
a chemical element with the symbol Gd and atomic number 64
Indium
a soft, malleable metal with a brilliant lustre
Nihonium
a synthetic chemical element with the symbol Nh and atomic number 113