The periodic table is filled with fascinating elements, each with its own role in science and everyday life. But while some are common and widely used, others are extremely rare—found in tiny amounts on Earth or created only in labs. These rare elements often have unusual properties, high value, or important uses in technology, medicine, or research.
In this article, we’ll explore some of the rarest elements on the periodic table and what makes them so special.
| Element | Symbol | Atomic Number | Key Fact |
|---|---|---|---|
| Astatine | At | 85 | Rarest naturally occurring non-transuranic element; half-life ~8 hours |
| Berkelium | Bk | 97 | First synthesized in 1949; produced only in billionths of a gram |
| Protactinium | Pa | 91 | Extremely rare and expensive; only 125g isolated from 60 tons of material |
| Rhodium | Rh | 45 | One of the most expensive metals; used mainly in plating and catalysts |
| Osmium | Os | 76 | Found in platinum ores; emits toxic osmium tetroxide in powder form |
| Iridium | Ir | 77 | Only 3 tons produced annually; used in high-temperature alloys |
| Oganesson | Og | 118 | Synthetic superheavy element; half-life less than 1 millisecond |
| Francium | Fr | 87 | Extremely rare; only trace amounts exist naturally |
| Technetium | Tc | 43 | First artificial element; used in medical imaging |
| Neptunium | Np | 93 | First transuranic element; studied for nuclear waste management |
Astatine (At)
Astatine is one of the rarest naturally occurring elements on Earth, with an atomic number of 85. It sits in Group 17, making it a member of the halogen family, alongside chlorine and iodine.
Originally discovered in 1940, astatine is so rare that scientists estimate there are no more than 25 grams of it in Earth’s crust at any given time. It’s unstable and radioactive, with a half-life of about 8 hours, meaning it decays quickly into other elements. Even if you could get your hands on astatine, it would disappear in just a few days.
Its name comes from the Greek word astatos, meaning “unstable,” which perfectly describes its short-lived nature.
Berkelium (Bk)
Berkelium, atomic number 97, is a synthetic and radioactive transuranic element. It was first created in 1949 by a team of scientists—Stanley G. Thompson, Glenn T. Seaborg, Kenneth Street Jr., and Albert Ghiorso—at the University of California, Berkeley.
They produced it by bombarding americium-241 with alpha particles in a cyclotron, forming berkelium-243. Its most stable isotope, berkelium-247, has a half-life of about 1,380 years.
Berkelium has no commercial applications and is produced only in extremely small quantities for research purposes. In fact, the first visible amount of a berkelium compound—berkelium chloride—weighed just three billionths of a gram.
Protactinium (Pa)
Protactinium, symbol Pa and atomic number 91, is a rare and highly radioactive element. It was first discovered in 1913 and later isolated in a more stable form in 1917/1918.
It appears as a silvery-gray metal and becomes superconductive below 1.4 K. Though it occurs naturally in uranium ores, it’s found only in trace amounts.
In 1961, the UK Atomic Energy Authority processed 60 tons of waste material to isolate just 125 grams of pure protactinium. It cost them around $500,000. Its extreme rarity, high toxicity, and intense radioactivity make it useful only for scientific research.
Rhodium (Rh)
Discovered in 1803 by William Hyde Wollaston, rhodium is a rare, silvery-white metal with atomic number 45. It’s typically found as a byproduct of platinum and nickel mining.
Rhodium is one of the most expensive metals in the world, often trading at prices ten times higher than gold. It’s a noble metal, meaning it resists corrosion and oxidation.
While too brittle to make solid jewelry, it’s prized for jewelry plating due to its mirror-like shine. Rhodium is also used in catalytic converters, electrical contacts, and alloys with platinum or palladium for high-temperature equipment.
Osmium (Os)
With atomic number 76, osmium is part of the platinum group metals. It’s a dense, hard, brittle metal with a bluish tint.
First discovered in 1803 by Smithson Tennant, osmium is extracted from platinum ore or nickel mining. In powdered form, it emits osmium tetroxide, a toxic and pungent compound—hence its name, derived from the Greek osme, meaning “smell.”
Due to its rarity and toxicity, osmium is mostly used in alloys for specialized products like fountain pen tips, record player needles, and electrical contacts.
Iridium (Ir)
Iridium, atomic number 77, was discovered alongside osmium in 1803. It is incredibly rare, with only about three tons produced globally each year.
In its pure form, iridium is very brittle and hard to work with. It’s mainly used in alloys with platinum, making it ideal for crucibles, spark plug electrodes, and other high-temperature applications. Iridium is also used with osmium to make durable pen tips and compass bearings.
Oganesson (Og)
Oganesson, symbol Og and atomic number 118, is one of the newest and rarest elements. It was temporarily named Ununoctium before being renamed in 2016 to honor Russian physicist Yuri Oganessian.
It was first synthesized in 2006 by a Russian-American team who bombarded californium-249 with calcium-48 ions. The resulting oganesson-294 has a half-life of less than a millisecond.
This superheavy element has no known practical uses and is produced only for theoretical research in nuclear physics.
Francium (Fr)
With atomic number 87, francium is another naturally occurring but extremely rare element. Discovered in 1939 by French physicist Marguerite Perey, it’s typically found in uranium and thorium ores—but only in minute amounts.
Francium’s most stable isotope, francium-223, has a half-life of just 22 minutes. Due to its radioactivity and scarcity, it has no commercial applications and is used only in nuclear research.
Technetium (Tc)
Technetium, atomic number 43, was the first element to be artificially produced. It was discovered in 1937 by Italian scientists Emilio Segrè and Carlo Perrier.
Today, it’s produced by bombarding molybdenum-98 with neutrons, creating technetium-99, a radioactive isotope used in medical imaging.
Though technetium can prevent steel corrosion, its radioactivity limits broader applications. It’s mainly used in closed systems, calibration, and as a radioactive tracer in nuclear medicine.
Neptunium (Np)
Neptunium, with atomic number 93, was the first transuranium element to be synthesized. It was discovered in 1940 by Edwin McMillan and Philip H. Abelson at Berkeley.
Named after the planet Neptune, it’s formed by bombarding uranium with neutrons in nuclear reactors. Its most stable isotope, neptunium-237, has a half-life of 2.14 million years.
Though rare, neptunium is studied for potential use in nuclear waste management and reactor fuel systems.
Interesting Facts About the Periodic Table
Beyond its well-acknowledged scientific significance, the periodic table harbors a multitude of fascinating stories, groundbreaking discoveries, and intriguing facts. Here are ten interesting facts about the periodic table that highlight its complexity, history, and the curious tidbits that make it endlessly fascinating.
- Mendeleev’s Dream: Dmitri Mendeleev, the father of the periodic table, claimed that the idea of arranging the elements came to him in a dream. He woke up and immediately wrote down what would become the foundation of modern chemistry.
- Element Naming Controversies: The naming of elements has not always been straightforward, leading to disputes. For instance, element 106 was contested between American and Soviet scientists, eventually named Seaborgium (Sg) in honor of American chemist Glenn T. Seaborg.
- Gallium’s Spoon Trick: Discovered in 1875 by Lecoq de Boisbaudran, gallium has a melting point of approximately 29.76°C (85.57°F), allowing it to melt in your hand or when used to make a spoon dipped in hot tea.
- Only One Letter: The periodic table features only one element with a single-letter symbol: Hydrogen (H).
- Newest Members: As of my last update, the most recently added elements are Nihonium (Nh), Moscovium (Mc), Tennessine (Ts), and Oganesson (Og), completing the seventh row of the periodic table in 2016.
- Element 61, A Missing Piece: Promethium, element number 61, was one of the last naturally occurring elements to be discovered, filling a gap in the periodic table in 1945.
- The Noblest of Them All: Helium (He) is the only element that was first discovered outside of Earth, observed in the sun’s spectrum before it was found on our planet.
- Mercury’s Liquid Form: Among all the elements, only mercury (Hg) is liquid at room temperature, making it unique in its category.
- Artificially Created Elements: Elements beyond uranium (element 92) are not found in nature and have been synthesized in laboratories, showcasing human ingenuity in expanding the periodic table.
- Universe’s Building Blocks: Hydrogen and helium, the two simplest elements, make up about 99% of the known universe, highlighting the simplicity at the heart of cosmic complexity.
Conclusion
The periodic table holds more than just familiar names like carbon and iron. Hidden within it are elements so rare that they exist in only trace amounts or are created briefly in labs. While many of these elements have no practical use outside of scientific research, they offer insight into the building blocks of the universe.
Whether naturally occurring or synthetic, stable or fleeting, these rare elements remind us of how much we still have to learn—and discover—about the matter that surrounds us.