Category
page 1Metallic elements

metal
thumb|right|alt=refer to caption|Iron, shown here as fragments and a 1 cm3 cube, is an example of a [[chemical element that is a metal.]]
thumb|right|alt=A metal gravy boat|Metal in the form of a gravy boat made from [[stainless steel, an alloy largely composed of iron, chromium and nickel]]

thulium
Thulium is a chemical element; it has symbol Tm and atomic number 69. It is the thirteenth element in the lanthanide series of metals. It is the second-least abundant lanthanide in the Earth's crust, after radioactively unstable promethium. It is an easily workable metal with a bright silvery-gray luster. It is fairly soft and slowly tarnishes in air. Despite its high price and rarity, thulium is used as a dopant in solid-state lasers. It has no significant biological role and is not particularly toxic. Artificial radioactive isotopes of thulium are used as radiation sources in some portable X
rare earth element
any of the fifteen lanthanides plus scandium and yttrium
heavy metal
loosely defined subset of elements that exhibit metallic properties
post-transition metal
category of metallic elements