Terbium (Tb)

Terbium is a chemical element with the atomic number 65 in the periodic table. It’s one of the least plentiful rare-earth metals that occur in Earth’s crust. Located between the elements gadolinium and dysprosium, terbium is classified as a member of the lanthanide series of the periodic table. This rare-earth metal has three valence electrons … Read more

Dysprosium (Dy)

Dysprosium is a chemical element with an atomic number of 66 in the periodic table of elements. It’s one of the more abundant lanthanide elements found in Earth’s crust, in a concentration of 3 parts per million. Still, it never occurs in its free elemental form. Classified in the heavy rare-earth elements group (HREE), this … Read more

Holmium (Ho)

Holmium is a chemical element with an atomic number of 67 in the periodic table. It’s not found in the Earth’s crust. Classified as a member of the lanthanide series of elements, this rare-earth metal is a divalent substance with a +3 oxidation state, strong magnetic properties, and astounding stability of its electron shell.  Chemical … Read more

Erbium (Er)

Erbium is a radioactive chemical element with an atomic number of 68 in the periodic table of elements. This rare-earth element is found in the quantity of 3.8 ppm in Earth’s crust (0.0003%). Being a member of the lanthanides family of the periodic table, erbium is also classified as a transition metal.  Chemical and Physical … Read more

Thulium (Tm)

Thulium is a chemical element with atomic number 69 in the periodic table. It is found in Earth’s crust in almost the same quantities as the elements iodine and antimony, with an occurrence of around 500 parts per million.  Being a member of the lanthanide series of periodic table elements, this rare earth metal has … Read more

Ytterbium (Yb)

Ytterbium is a chemical element with the atomic number 70 in the periodic table. It’s the 44th most plentiful metal found in Earth’s crust. Being a member of the lanthanides family of elements, this rare-earth metal is a divalent substance with a high energy-level atomic structure that resembles the one of the element strontium. Element … Read more

Lutetium (Lu)

Lutetium is a chemical element with atomic number 71 in the periodic table. This rare-earth metal occurs in a concentration of 0.8 to 1.7 ppm in Earth’s crust. As a member of the lanthanides family of periodic table elements, lutetium has three valence electrons. Its most significant practical applications include the dating of meteorites and … Read more

Thorium (Th)

Thorium is a chemical element with the atomic number 90 in the periodic table. The average concentration of this substance in the upper crust of Earth amounts to 10.5 ppm, while thorium concentration in the middle layer (the mantle) is around 6.5 ppm. The core (lowest layer) of the Earth’s crust contains 1.2 ppm on … Read more

Protactinium (Pa)

Protactinium (formerly: protoactinium) is a chemical element with the atomic number 91 in the periodic table. With an approximate abundance of a few parts per trillion, it’s one of the rarest naturally occurring elements in Earth’s crust.  This member of the actinides family of periodic table elements is a poisonous and expensive chemical that emits … Read more

Uranium (U)

Uranium is a chemical element with the atomic number 92 in the periodic table. This substance makes up about two parts per million of Earth’s crust. Uranium in the layers of Earth is as common as the elements tin, tungsten, and molybdenum. As a member of the actinide series of periodic table elements, this naturally … Read more