Astatine is a chemical element with the symbol At and atomic number 85. It is the rarest naturally occurring element in the Earth's crust, occurring only as the decay product of various heavier elements.
Ununennium, or element 119, is a predicted chemical element. Its symbol is Uue. Ununennium and Uue are substitute names made by the IUPAC, (meaning "one-one-nine-ium" in Latin) until permanent names are made. Ununennium is the element with the smallest atomic number that has not been created yet.
Since element 123 is unknown, it has no biological role.
Despite several attempts, unbibium has not yet been synthesized, nor have any naturally occurring isotopes been found to exist. There are currently no plans to attempt to synthesize unbibium.
The first rare-earth mineral discovered (1787) was gadolinite, a black mineral composed of cerium, yttrium, iron, silicon, and other elements.
Astatine is the rarest element on Earth; only approximately 25 grams occur naturally on the planet at any given time. Its existence was predicted in the 1800s, but was finally discovered about 70 years later.
Uranium was discovered in 1789 by German chemist Martin Heinrich Klaproth. It is the heaviest naturally occurring element in the universe and is naturally radioactive. Its nucleus is unstable, so the element is in a constant state of decay, seeking a more stable arrangement.
As the earth's crust is estimated to mass around 2.6 * 1022 kg, it means that there is around 400 billion kg of gold throughout the entire crust. Much of it will never really be accessible, of course, but there really is quite a bit out there.
Platinum is an extremely rare metal, occurring at a concentration of only 0.005 ppm in Earth's crust.
If translated into numbers, platinum—for all of its known deposits—is considerably more rare than gold and is the rarest metal of all.
The rarest stable metal is tantalum. The rarest metal on earth is actually francium, but because this unstable element has a half life of a mere 22 minutes, it has no practical use.
Platinum Group Metals. Osmium, iridium, palladium, ruthenium and rhodium are typically grouped with platinum and known as platinum-group metals or elements (PGMs or PGEs). These elements are rare on earth, but abundant in the rest of the universe.
Iridium is one of the rarest elements on Earth. It is found uncombined in nature in sediments that were deposited by rivers. It is commercially recovered as a by-product of nickel refining. A very thin layer of iridium exists in the Earth's crust.
Almost every galaxy can be classified as a spiral, elliptical, or irregular galaxy. Only 1-in-10,000 galaxies fall into the rarest category of all: ring galaxies.
Scientific element: Francium
The most expensive and second rarest natural element.
Plutonium. Pretty much all of the radioactive elements are cool. Plutonium is particularly awesome because it truly does glow in the dark.
The principal economic sources of rare earths are the minerals bastnasite, monazite, and loparite and the lateritic ion-adsorption clays. The rare earths are a relatively abundant group of 17 elements composed of scandium, yttrium, and the lanthanides.
Nothing. Rare Earth Elements (REE) are not rare at all. Despite the name, these elements – defined as the 15 lanthanides plus scandium (Sc) and yttrium (Y) – are not as rare as one might think. Although originally thought to be rare, many of the minerals are actually common in the Earth's crust.
The last naturally occurring rare-earth element (lutetium) was discovered in 1907, but research into the chemistry of these elements was difficult because no one knew how many true rare-earth elements existed.
Did you know that uranium is the heaviest naturally-occurring metal? It is more than 40 times heavier than lead and nine times heavier than gold. The element has an atomic number of 92 and an atomic weight of 238.056.
Indium - Element information, properties and uses | Periodic Table.
A synthetic element is one of 24 known chemical elements that do not occur naturally on Earth: they have been created by human manipulation of fundamental particles in a nuclear reactor, a particle accelerator, or the explosion of an atomic bomb; thus, they are called "synthetic", "artificial", or "man-made".