H
Hydrogen
Fun Fact: Despite all the nuclear fusion that has occurred in stars since the big bang, hydrogen is still by far the most abundant element in the universe, and makes up four-fifths of all ordinary matter. For a while it was touted as the fuel of the future, but it remains difficult to produce, transport and store. At extreme temperatures and pressures, like those at the core of a gas-giant planet, hydrogen can become metallic.
| Phase | Gas |
| Category | Alkali Metal |
| Atomic Weight | 1.00794(7) |
X
He
Helium
Fun Fact: It is not the lightest of all elements, but it is the smallest: it has a stronger electrostatic charge in its nucleus than hydrogen does, and thus it keeps its electrons in a tighter orbit. Helium has numerous applications but its global supply is in critical shortage.
X
Li
Lithium
Fun Fact: One of only three elements to be created in the big bang, though in much smaller amounts than hydrogen or helium. It has no known role in normal physiology, but as a drug it has long been appreciated as a mood stabilizer. Dilithium, or Li2, is a gas; unfortunately there is no such thing as a dilithium crystal.
X
Be
Beryllium
Fun Fact: This element is the first one that requires more neutrons than protons in its nucleus in order to be stable, and thus it created a bottleneck in the formation of new elements after the big bang. It gives emeralds their green or red hues and aquamarine its light blue. Its resistance to extreme cold temperature makes it ideal for space telescope mirrors, including those of the James Webb Space Telescope.
X
B
Boron
Fun Fact: This element is fairly rare and has no known role in biology. Mixed in with glass, it reduces thermal expansion and thus it makes for oven-proof pots and pans.
X
C
Carbon
Fun Fact: By some estimates, more than 80 percent of known molecules are carbon based, or “organic” (which does not necessarily imply biological origin). Carbon is so omnipresent in molecular structures that chemists do not even bother to label it.
X
N
Nitrogen
Fun Fact: In its molecular form, N2, it is extremely tough to break up, which makes it essentially inert—a good thing given that N2 makes up nearly 80 percent of the atmosphere. Nitrogen-based compounds are one of the main pollutants in artificial fertilizer runoff.
X
O
Oxygen
Fun Fact: The element that gave oxidation its name is not required in it; anything that steals electrons away performs oxidation. Oxygen is the third most abundant element in the universe and may be the most abundant in the composition of Earth—though iron is often estimated to beat it.
X
F
Fluorine
Fun Fact: The “tiger of chemistry” is the most reactive of all elements; it even reacts which some of the heavier noble gases. Chemists spent a century trying to isolate it, and several died in the attempt. Fluorine also forms some of the most tenacious molecular bonds, making fluorine-based pollutants such as the non-stick coating Teflon especially hard to dispose.
X
Ne
Neon
Fun Fact: Like helium, it is a true noble gas—it is chemically inert as an isolated atom and does not form chemical bonds. It is “mined” from the atmosphere, and its fluorescence makes it ideal for lamps.
X
Na
Sodium
Fun Fact: Like all elements in its column, called the alkalis, it is only stable if it has donated one of its outer electrons. On the opposite side of the periodic table, the halogens, such as chlorine, need to capture one electron for stability. That complementarity makes for an ideal marriage, and one common result is a salt—such as sodium chloride, shown here.
X
Mg
Magnesium
Fun Fact: Another top-10 element in the Earth’s crust, it also has hundreds of roles in living cells, including human cells. In plants, every chlorophyll molecule has a magnesium ion at its heart.
X
Al
Aluminium
Fun Fact: It is the most abundant metal in Earth’s crust but it is rare in its pure form. Until the 1800s, when the technology was developed to separate it from rock, it was more expensive than gold; Napoleon III allegedly hosted a banquet in which the guests of honor ate on aluminum plates.
X
Si
Silicon
Fun Fact: Most of the Earth’s rock and mantle is made of silicate rock: Earth is classified as a silicate planet. Although it is chemically similar to carbon, which is the basis of biological chemistry, chemists doubt that silicon-based life could exist.
X
P
Phosphorus
Fun Fact: One of the crucial building blocks of DNA as well as of ATP, the living cell’s main form of energy currency. Together with nitrogen compounds, phosphates are a major pollutant in the runoff from fertilizers, causing “dead zones” in seas and lakes.
X
S
Sulfur
Fun Fact: Before photosynthesis appeared, hydrogen sulfite (H2S) may have been life’s first source of energy. Sulfur is one of the most important elements in the living cell, appearing in two types of amino acids and in countless other compounds.
X
Cl
Chlorine
Fun Fact: It was the first chemical weapon to find use in World War I, but it has also long been one of humanity’s best friends, beginning with the treatment of cholera-infested water wells in London in the mid-1800s. Chlorofluorocarbons were banned in 1996 after being linked to damage of the ozone layer.
| Phase | Gas |
| Category | Halogens |
| Atomic Weight | 35.453(2) |
X
Ar
Argon
Fun Fact: The third of noble gases, it was considered completely inert until in 2000 when Finnish chemists showed that it does form compounds with hydrogen fluoride—though only at -265 degrees Celsius.
| Phase | Gas |
| Category | Noble Gases |
| Atomic Weight | 39.948(1) |
X
K
Potassium
Fun Fact: Together with nitrogen and phosphorus it is one of the three crucial elements in artificial fertilizers, which often go by the name of N-P-K. It is part of the alkali column, whose name comes from qali, the Arabic word for the salt-loving plant saltwort.
| Phase | Solid |
| Category | Alkali Metals |
| Atomic Weight | 39.0983(1) |
X
Ca
Calcium
Fun Fact: Like phosphorus, it is an ingredient of hydroxylapatite, the mineral that makes up 50 percent of bone mass as well as dental enamel. It locks up Earth’s largest carbon reservoir of biological origin in the form of calcium carbonate, aka chalk (the stuff that makes the White Cliffs of Dover white).
X
Sc
Scandium
Fun Fact: Its existence was predicted by Mendeleyev before its discovery, based on the structure of the periodic table. It is one of only two elements—the other being Yttrium—to be classified as rare earths that lie outside of the lanthanoid group. It was allegedly used for the noses of Soviet submarine-carried ICBMs, enabling them to ram through sea ice.
| Phase | Solid |
| Category | Transition Metals |
| Atomic Weight | 44.955912(6) |
X
Ti
Titanium
Fun Fact: As titanium dioxide, it is the main ingredient of white paint as well as sunblock. Titanium’s light weight, strength and resistance to corrosion also make it a favorite material for the structural elements of aircraft.
X
V
Vanadium
Fun Fact: An important ingredient in the fluid that stores energy in flow batteries, a technology that might some day store vast amounts of energy from solar panels and wind farms for later use.
| Phase | Solid |
| Category | Transition Metals |
| Atomic Weight | 50.9415(1) |
X
Cr
Chromium
Fun Fact: This famously colorless metal is, ironically, named after the Greek word for color. Indeed, its compounds include numerous pigments, including the traditional “chrome yellow” of U.S. school buses.
| Phase | Solid |
| Category | Transition Metals |
| Atomic Weight | 51.9961(6) |
X
Mn
Manganese
Fun Fact: It plays a crucial but poorly understood role in photosynthesis—specifically, in the molecular complexes that split water molecules using solar energy.
| Phase | Solid |
| Category | Transition Metals |
| Atomic Weight | 54.938045(5) |
X
Fe
Iron
Fun Fact: In stars, nuclear fusion releases energy by producing heavier and heavier elements, until it stops at iron: other processes are required to synthesize the higher elements. Rusting iron is the single largest sink of the oxygen in Earth’s atmosphere.
X
Co
Cobalt
Fun Fact: Its name may originate from the German word for “goblin.” It is one of the rarest transition metals, and an essential ingredient of vitamin B12.
X
Ni
Nickel
Fun Fact: Bacteria that have carbon dioxide, carbon monoxide or methane as their source of energy all use nickel-based enzymes in their metabolism.
X
Cu
Copper
Fun Fact: Many invertebrates—including octopi and horseshoe crabs—are literally blue-blooded. They transport oxygen in their blood using a bluish, copper-based molecule called hemocyanin rather than the iron-based hemoglobin. Hemocyanin is more efficient than hemoglobin at storing oxygen in deep, cold waters.
X
Zn
Zinc
Fun Fact: This element might have been refined in India as early as the 12th century. It is used in galvanization, a form of rust proofing.
| Phase | Solid |
| Category | Transition Metals |
| Atomic Weight | 65.38(2)(4) |
X
Ga
Gallium
Fun Fact: It is solid at room temperature but has a melting point of just 29 degrees Celsius, which gave inspiration for the title of a recent book on the periodic table, The Disappearing Spoon. In 1997, masked thieves broke into a physics lab in Russia and attempted to siphon off 60 tons of highly purified liquid gallium from a neutrino detector—a booty that would have been worth $30 million.
| Phase | Solid |
| Category | Post-Transition Metals |
| Atomic Weight | 69.723(1) |
X
Ge
Germanium
Fun Fact: Its existence was predicted by Mendeleyev before its discovery, based on the structure of the periodic table. It is a semiconductor, used primarily in diodes.
| Phase | Solid |
| Category | Metalloids |
| Atomic Weight | 72.63(1) |
X
As
Arsenic
Fun Fact: One of the most popular poisons throughout the ages, so much so that it was often called “inheritance powder”; one of its inadvertently deadly uses—as a coloring for wallpaper—may have resulted in the death of Napoleon. A recent, controversial study suggested that some bacteria may use arsenic in place of phosphorus.
X
Se
Selenium
Fun Fact: The most stable form of this element is a semiconductor used in photovoltaic cells because it conducts electricity better in the light than in the dark.
X
Br
Bromine
Fun Fact: This element is a favorite of hot-tubbers because it has sanitizing properties similar to those of chlorine but it is not as smelly.
X
Kr
Krypton
Fun Fact: Even though it is a noble gas, it does form compounds—though not the oxide that would qualify to be called kryptonite, the fictional material that Superman loves to hate.
| Phase | Gas |
| Category | Noble-Gases |
| Atomic Weight | 83.798 |
X
Rb
Rubidium
Fun Fact: Atoms of the rubidium-87 isotope naturally repel each other. This property made physicists pick them for the first demonstration of the ultra-cold state of matter known as a Bose-Einstein condensate, which is at its lowest possible energy state and consequently displays quantum effects such as wavelike behavior.
| Phase | Solid |
| Category | Alkali Metals |
| Atomic Weight | 85.4678(3) |
X
Sr
Strontium
Fun Fact: It gives stadium flares their brilliant red hues. Its radioactive isotope Sr-90 is notorious for accumulating in the bones, owing to strontium’s chemical similarities with calcium.
| Phase | Solid |
| Category | Alkaline Earth Metals |
| Atomic Weight | 87.62 |
X
Y
Fun Fact: This is one of four elements named after the small Swedish town of Ytterby (the others are ytterbium, erbium and terbium). Yttrium barium copper oxide was the first material found to be a superconductor at high enough temperatures to be kept in liquid nitrogen instead of the more cumbersome liquid helium.
| Phase | Solid |
| Category | Transition Metals |
| Atomic Weight | 88.90585 |
X
Zr
Fun Fact: Most of its use goes into nuclear reactors, because of its resistance to radiation and corrosion at high temperatures.
| Phase | Solid |
| Category | Transition Metals |
| Atomic Weight | 91.224 |
X
Nb
Niobium
Fun Fact: Named after the Greek goddess Niobe, daughter of Tantalus; the element tantalum is located directly below it. One of the elemental superconductors, it is used in the radio-frequency cavities of some of the most advanced liquid-helium–cooled particle accelerators.
| Phase | Solid |
| Category | Transition Metals |
| Atomic Weight | 92.90638 |
X
Mo
Molybdenum
Fun Fact: This element is found in dozens of important enzymes in the human body. Since World War I it has been used as a steel hardener.
| Phase | Solid |
| Category | Transition Metals |
| Atomic Weight | 95.94(1) |
X
Tc
Technetium
Fun Fact: None of this element’s isotopes are stable. It was first discovered by creating it in the laboratory, although later it was found to occur naturally in trace amounts, as a decay product of the spontaneous fission of uranium.
X
Ru
Ruthenium
Fun Fact: The element was named after Russia (its Latin name is Ruthenia) because it was first discovered in Siberian platinum. In 1944 it was included in the ballpoints of Parker pens for its strength and durability.
X
Rh
Rhodium
Fun Fact: This element is one of the rarest precious metals, and the most precious, typically 60 percent more costly than platinum. Small amounts are used in catalytic converters.
| Phase | Solid |
| Category | Transition Metals |
| Atomic Weight | 102.90550 |
X
Pd
Fun Fact: Chemists have used palladium’s wonders as a catalyst to synthesize organic molecules that until recently only living cells could produce. This work earned Richard F. Heck, Ei-ichi Negishi and Akira Suzuki the 2010 Nobel Prize in Chemistry.
X
Ag
Silver
Fun Fact: In 2000, Stan Jones, a Montana libertarian politician who was running for the U.S. Senate, intentionally ingested silver as an antibiotic, which turned his skin permanently blue. Silver is also an excellent catalyst, which accounts for more use of silver than jewelry.
X
Cd
Cadmium
Fun Fact: Mostly known for its use in blue pigments, it is one of the toxic “heavy metals.” In summer 2010 McDonald’s recalled more than 12 million Shrek 3 glasses due to cadmium contamination.
| Phase | Solid |
| Category | Transition Metals |
| Atomic Weight | 112.411 |
X
In
Indium
Fun Fact: Bulk indium can trap an electron inside it as if it were orbiting an artificial atom. Physicists use the effect in the creation of “quantum dots,” one of the main approaches to building quantum computers.
X
Sn
Tin
Fun Fact: Most ancient civilizations learned to smelter alloys of tin and copper before they did iron, giving the Bronze Age its name. As lead is phased out due to its toxicity, tin is replacing it in applications such as solder.
| Phase | Solid |
| Category | Post-Transition Metals |
| Atomic Weight | 118.710 |
X
Sb
Antimony
Fun Fact: A compound of antimony and fluoride is one of the most acidic known, with a pH of -31. In alchemy it was seen as a feminine element; its symbol later became the symbol for “female” (a cross with a circle on top).
| Phase | Solid |
| Category | Metalloids |
| Atomic Weight | 121.760(1) |
X
Te
Tellurium
Fun Fact: It is the only element that easily forms minerals with gold; most gold ore comes in the form of gold telluride. The radioactive isotope tellurium-128 has the longest known half-life of any known unstable isotope, at 2.2 septillion years, or 2.2X10^24 years. A small amount of tellurium, if spilled on the skin, makes you smell of garlic for weeks.
X
I
Iodine
Fun Fact: It is responsible for the characteristic smell of seaweeds. It is an essential micronutrient, most of it used in the thyroid for the production of hormones.
X
Xe
Xenon
Fun Fact: This element is Oliver Sacks’ favorite because it was the first noble gas to be shown to form chemical bonds, reminding the author of how he overcame his solitary nature.
X
Cs
Fun Fact: The “other golden metal”: it is one of only three metals—the others being gold and copper—to have a color other than gray or shiny silver. It is used in the most precise atomic clocks, which lose or gain less than a second every 138 million years.
| Phase | Solid |
| Category | Alkali Metals |
| Atomic Weight | 132.9054519(2) |
X
Ba
Fun Fact: In the middle ages pebbles found near Bologna, Italy, were highly coveted by witches and alchemists alike because after being exposed to light can they glow in the dark for years. The stones turn out to be made of barite, or barium sulfite. Traces of barite in marine sediments give an indication of the ocean’s productivity throughout the ages.
X
La
Lanthanum
Fun Fact: The family of lanthanide elements in the periodic table gets its name from it. Lanthanum is used for the anodes of nickel-metal hydride batteries: a Toyota Prius may contain more than 30 pounds of it.
| Phase | Solid |
| Category | Lanthanides |
| Atomic Weight | 138.90547 |
X
Ce
Cerium
Fun Fact: The most abundant of the lanthanides, it is as common in Earth’s crust as copper. It is used in high-intensity lamps of film projectors.
X
Pr
Fun Fact: Crystals of silicate “doped” with praseodymium have been used to slow light to just a few hundred meters per second. It also finds applications in goggles for welders.
| Phase | Solid |
| Category | Lanthanides |
| Atomic Weight | 140.90765 |
X
Nd
Neodymium
Fun Fact: One of the rare-earth metals whose use in high-tech applications has been booming in recent years. Neodymium magnets are the strongest permanent magnets known and they are used in microphones, loudspeakers, headphones and computer hard disks. A Toyota Prius contains more than two pounds of it.
| Phase | Solid |
| Category | Lanthanides |
| Atomic Weight | 144.242 |
X
Pm
Promethium
Fun Fact: Together with technetium, it is the only relatively light element in the table that has no stable isotopes. Like astatine, it occurs in the Earth’s crust only as a fleeting product of the decay of other elements; scientists have estimated that less than 600 grams of it exist on the entire planet at any given time.
| Phase | Solid |
| Category | Lanthanides |
| Atomic Weight | [145] |
X
Sm
Samarium
Fun Fact: Its isotope samarium-148 is radioactive with a half-life of seven quadrillion years—20 million times as long as the age of the universe. Samarium-147, with a half-life of “just” 106 billion years, is used in the samarium-neodymium dating of rocks and meteorites.
| Phase | Solid |
| Category | Lanthanides |
| Atomic Weight | 150.36 |
X
Eu
Europium
Fun Fact: Euro banknotes are rumored to contain europium (fittingly!) as an anti-counterfeit measure, because of the element’s fluorescent signature--although analyzing the notes’ chemistry would be illegal.
X
Gd
Gadolinium
Fun Fact: This rare-earth element is magnetic at room temperature but holding it in your hand warms it enough for it to lose its magnetism.
| Phase | Solid |
| Category | Lanthanides |
| Atomic Weight | 157.25 |
X
Tb
Terbium
Fun Fact:
| Phase | Solid |
| Category | Lanthanides |
| Atomic Weight | 158.92535 |
X
Dy
Dysprosium
Fun Fact: Its name originates from the Greek “hard to get”: in 1866 it took French chemist Paul Émile Lecoq de Boisbaudran more than 30 attempts to isolate it form other rare earths. It is used in the fabrication of certain lasers and computer hard disks.
X
Ho
Holmium
Fun Fact: It can acquire the strongest magnetization of any element, but it does not stay permanently magnetized. It is used as a dopant of crystals in high-performance lasers.
| Phase | Solid |
| Category | Lanthanides |
| Atomic Weight | 164.93032 |
X
Er
Fun Fact: One of four elements named after Ytterby, Sweden, where they were discovered (the other three being ytterbium, yttrium and terbium). Erbium has fluorescent bands in the infrared spectrum, right where optical fibers are most efficient—making erbium lasers a cornerstone of the Internet infrastructure.
| Phase | Gas |
| Category | Lanthanides |
| Atomic Weight | 167.259 |
X
Tm
Thulium
Fun Fact: The radioactive isotope thulium-170, produced by bombarding naturally-occurring thulium-169 with neutrons, is used in portable x-ray machines. It is one of the few truly rare elements among the rare earths.
| Phase | Solid |
| Category | Lanthanides |
| Atomic Weight | 168.93421 |
X
Yb
Ytterbium
Fun Fact: It is more common in the Earth’s crust than tin, bromine, uranium or arsenic. But like other rare-earth elements, it has little tendency to accumulate in ore deposits, which makes its mining tricky expensive. Like erbium, it is used in infrared lasers for fiber-optic networks.
| Phase | Solid |
| Category | Lanthanides |
| Atomic Weight | 173.054(5) |
X
Lu
Lutetium
Fun Fact: This element is the last, and rarest, of the rare-earth elements—although it is still more abundant than gold. In September 2010, China, which has a near-monopoly of the production of rare earths, caused widespread alarm when it announced a possibly illegal export ban.
| Phase | Solid |
| Category | Lanthanides |
| Atomic Weight | 174.9668(4) |
X
Hf
Hafnium
Fun Fact: Its existence and chemical properties were predicted by Mendeleyev before its discovery, based on the structure of the periodic table. Hafnium oxide is a high-performance electrical insulator, which, starting in 2007, has enabled engineers to pack more transistors into computer chips.
| Phase | Solid |
| Category | Transition Metals |
| Atomic Weight | 178.49 |
X
Ta
Fun Fact: It is an excellent conductor of both heat and electricity, and its use contributed to making cell phones smaller and lighter. It is also chemically inert, which makes it ideal for implants such as pacemakers.
| Phase | Solid |
| Category | Transition Metals |
| Atomic Weight | 180.94788 |
X
W
Tungsten
Fun Fact: This element has the highest melting point of all elements, at 6,170 degrees Fahrenheit (3,410 degrees Celsius) and is the heaviest element to be used by living organisms. It is one of the few elements that commonly go under two names, the other one being wolfram—hence the W symbol.
X
Re
Rhenium
Fun Fact: It is one of the rarest elements in the Earth’s crust, and was the last naturally occurring stable element to be discovered (in 1925). It has the highest boiling point of any element, at 5,596 degrees Celsius. Its main use is in special alloys for jet engines.
X
Os
Osmium
Fun Fact: It is the densest of the elements—more than 22 times denser than water—and it is the least abundant stable element in the Earth’s crust. (Radioactive elements such as astatine, promethium and technetium are even less abundant.) The stylus in early phonographs was made of osmium.
X
Ir
Iridium
Fun Fact: It is rare in Earth’s crust but not in asteroids. Thus when, in 1980, a team led by physics Nobel Prize winner Luis Alvarez discovered a thin geological layer of iridium lying at the boundary between sediments from the Cretaceous and the Tertiary eras worldwide, the researchers formulated the impact hypothesis for the extinction of dinosaurs.
| Phase | Solid |
| Category | Transition Metals |
| Atomic Weight | 192.217 |
X
Pt
Platinum
Fun Fact: This element is one of chemists’ favorite catalysts. In catalytic converters, platinum breaks down hydrocarbon residues in exhaust fumes into carbon dioxide and water vapor.
X
Au
Gold
Fun Fact: It is one of the most inert metals when in bulk. But gold nanoparticles have surprising catalytic powers. They also assume different colors depending on their size: gold nanoparticles are responsible for the reds of stained glasses.
X
Hg
Mercury
Fun Fact: The U.S. Environmental Protection Agency recently proposed regulations on smokestack emissions of this metal, which can cause neurological disorders. Lewis and Clark took mercury laxative pills on their expedition, which later helped archeologists identify traces of their camping sites.
| Phase | Liquid |
| Category | Transition Metals |
| Atomic Weight | 200.59(2) |
X
Tl
Thallium
Fun Fact: It is regarded as the most toxic of all the elements—although radioactive elements such as polonium or plutonium are lethal at lower doses. In 1972 President Nixon issued an executive order that outlawed thallium’s use as a poison. It still finds numerous applications in electronics, however, for example in infrared detectors.
| Phase | Solid |
| Category | Post-Transition Metals |
| Atomic Weight | 204.3833 |
X
Pb
Lead
Fun Fact: Already in the mid-1800s, Emily Dickinson waxed poetic about the paralysis that can result from ingesting even tiny amounts of lead. Some historians have even blamed its use for the decline of the Roman Empire. This heavy metal however can also be good for you: it is one of the most commonly used materials for radiation shielding.
| Phase | Solid |
| Category | Post-Transition Metals |
| Atomic Weight | 207.2 |
X
Po
Polonium
Fun Fact: As is the case for radium, it was discovered by Pierre and Marie Curie. But it is even more intensely radioactive than radium; it was used to murder a Russian dissident in 2006. Polonium is present in tobacco leaves and easily inhaled as a component of cigarette smoke, probably causing at least some smoke-related lung cancers.
| Phase | Solid |
| Category | Metalloids |
| Atomic Weight | (209) |
X
At
Astatine
Fun Fact: Because of its short half-life, it is considered to be the rarest of all elements, even rarer than promethium: the entire planet is estimated to hold just one ounce of astatine at any given time.
X
Rn
Radon
Fun Fact: A product of the decay chain of the uranium and thorium that are naturally present in the Earth’s crust, this radioactive noble gas seeps through the soil and tends to accumulate in poorly ventilated basements. It is considered to be the second most frequent cause of lung cancer.
| Phase | Gas |
| Category | Noble Gases |
| Atomic Weight | (222) |
X
Fr
Francium
Fun Fact: Its half-life is even shorter than that of astatine (the rarest element in nature), but it is not quite as rare because more of it is continuously produced by radioactive decay.
X
Ra
Radium
Fun Fact: After Pierre and Marie Curie discovered it in 1898, radium was embraced enthusiastically by inventors for its wondrous properties, such as the fact that it glows in the dark. But starting in the 1920s people began to use it more cautiously after young female workers who had painted luminous watch dials began to die from the element’s radiation.
| Phase | Solid |
| Category | Alkaline Earth Metals |
| Atomic Weight | (226) |
X
Ac
Fun Fact: It is found in pitchblende, the same type of rock from which radium and polonium—the elements discovered by Pierre and Marie Curie—were first extracted. It gives its name to the actinides, the elements with atomic numbers between 89 and 103.
| Phase | Solid |
| Category | Actinides |
| Atomic Weight | (227) |
X
Th
Thorium
Fun Fact: Some see this radioactive, relatively common element as a promising substitute for uranium in a new generation of nuclear reactors. Its abundance, especially in Earth’s core, is difficult to estimate precisely, and leads to uncertainties about the rate at which the planet has cooled since its formation.
| Phase | Solid |
| Category | Actinides |
| Atomic Weight | 232.0381 |
X
Pa
Protactinium
Fun Fact: Even though it is located after thorium on the periodic table, protactinium has a lower atomic weight because its most prevalent isotopes have fewer neutrons in their nuclei—one of only four such cases in the periodic table. Its existence was predicted by Mendeleyev before its discovery, based on the structure of the periodic table.
X
U
Uranium
Fun Fact: Since the Manhattan Project, uranium has had sinister associations, and like all radioactive elements it is of course a health hazard. But for a while after radioactivity was discovered, some regarded it as beneficial. In the early 20th century, spas in the U.S. and Europe added uranium to their swimming pools, and people took it as a dietary supplement in “radioactive water.”
X
Np
Neptunium
Fun Fact: Its position between uranium and plutonium is not coincidental (it reflects the sequence of the corresponding planets). It was the first actinide to be synthesized, in 1940.
X
Pu
Plutonium
Fun Fact: It was long classified as an artificial element, until in 1972 when physicists discovered that some two billion years ago uranium deposits in Gabon must have undergone a sustained chain reaction, similar to what happens in a nuclear power station. Among the traces of that reaction the researchers found some plutonium.
X
Am
Americium
Fun Fact: This element was first produced (together with curium) in 1944 by Glenn T. Seaborg’s team using a 1.5-meter cyclotron at the University of California, Berkeley, Radiation Laboratory. Because the research was part of the Manhattan Project that created the atomic bomb, the discovery was not announced until after the World War II. Americium is used in smoke detectors.
| Phase | Solid |
| Category | Actinides |
| Atomic Weight | (243) |
X
Cm
Curium
Fun Fact: Curium was discovered together with americium. These two elements and the others with atomic numbers between 95 and 100 are produced by the decay by-products of nuclear explosions, such as heavy isotopes of uranium and plutonium. During the Cold War these elements could be detected in the atmosphere following nuclear tests. The heat released by curium has been used to produce power on board deep-space probes.
| Phase | Solid |
| Category | Actinides |
| Atomic Weight | (247) |
X
Bk
Berkelium
Fun Fact: In 1950 The New Yorker sarcastically remarked that Glenn T. Seaborg’s team had missed a chance to have four elements in a row named “universitium,” “ofium,” “californium” and “berkelium.” The team replied it did not want to risk naming the first two elements universitium and ofium lest the East Coast beat them to naming the next two “newium” and “yorkium.”
| Phase | Solid |
| Category | Actinides |
| Atomic Weight | (247) |
X
Cf
Californium
Fun Fact: This element also was discovered at the Berkeley Radiation Lab, which after World War II had become a research facility of the U.S. Atomic Energy Commission (the precursor of the Department of Energy). The intense neutron radiation produced by californium is used by oil companies in geophysical exploration, and by nuclear power stations to kick-start nuclear reactions.
| Phase | Solid |
| Category | Actinides |
| Atomic Weight | (251) |
X
Es
Einsteinium
Fun Fact: Although he was neither a chemist nor a nuclear physicist, Albert Einstein was the author of a seminal 1905 paper on Brownian motion that helped convince scientists of the existence of atoms and molecules. In the same year Einstein also laid the foundations for quantum theory, which eventually led scientists to explain the structure of the periodic table. Einsteinium was first discovered in materials from the fallout of a thermonuclear bomb.
| Phase | Solid |
| Category | Actinides |
| Atomic Weight | (252) |
X
Fm
Fermium
Fun Fact: Like einsteinium, fermium was first found in thermonuclear debris, but—unlike the elements that follow it in the periodic table—it can be produced in nuclear reactors as well. It may also be the highest-numbered element to have any practical application: its alpha particle emissions are used in radiotherapy.
| Phase | Solid |
| Category | Actinides |
| Atomic Weight | (257) |
X
Md
Mendelevium
Fun Fact: Researchers at the Berkeley Radiation Lab produced just 17 atoms of element 101, so they could detect it only by radioactive decay, instead of via the chemical techniques used for elements up to 100. In a gesture of Cold War détente—this was 1955—the team named it after Dimitry Mendeleyev, the Russian chemist wrote down the first periodic table after noticing patterns in the chemistry of elements when ordered according to atomic weight.
| Phase | Solid |
| Category | Actinides |
| Atomic Weight | (258) |
X
No
Nobelium
Fun Fact: Nobelium was named after the Nobel Institute of Physics in Stockholm, Sweden, even though that institute's claim to have synthesized it in 1957 was soon falsified by Berkeley Radiation Lab researchers. The Berkeley team got credited for nobelium's discovery, but in fact, the element had first been produced in 1956 at the Joint Institute for Nuclear Research (JINR) in Dubna, Russia.
| Phase | Solid |
| Category | Actinides |
| Atomic Weight | [259] |
X
Lr
Lawrencium
Fun Fact: Some chemists regard lawrencium as the last of the actinides, and thus place it at the bottom right of the two rows of elements that are displayed separately from the others, as here. Others point out that because of chemical properties lawrencium—together with element 71, lutetium—should be placed in the leftmost column of the transition metals, underneath scandium (21) and yttrium (39). It was found in 1961 at the Lawrence Berkeley National Laboratory—the new name for the Berkeley Radiation Lab—and is named after its founder Ernest Lawrence.
| Phase | Solid |
| Category | Actinides |
| Atomic Weight | [262] |
X
Rf
Rutherfordium
Fun Fact: This element is the first of several for which discovery was claimed by a team at the JINR, in 1964, but priority was contested by researchers at Lawrence Berkeley.
X
Db
Dubnium
Fun Fact: The Flerov Laboratory of Nuclear Reactions (part of the JINR) in Dubna, Russia, was founded by Georgy Flerov in the late 1950s and is now at the forefront of the creation of new elements. Discovered in the 1960s, element 105 was officially named dubnium in 1996 when the International Union of Pure and Applied Chemistry (IUPAC) settled a bitter, decades-long dispute between teams of scientists at Dubna and at Lawrence Berkeley.
| Phase | Unknown |
| Category | Transition Metals |
| Atomic Weight | [268] |
X
Sg
Seaborgium
Fun Fact: American chemist Glenn T. Seaborg contributed to the discovery of element 106 as well as of nine other elements—all those numbered 94 to 102. Chemists joked that one could address letters to Seaborg using exclusively chemical symbols: Sg, Bk, Cf, Am—for “Seaborg,” “University of California at Berkeley,” “California,” “America.” The name seaborgium for 106 was initially disputed by scientists who believed no element should be named after a living person.
| Phase | Solid |
| Category | Transition Metals |
| Atomic Weight | [271] |
X
Bh
Bohrium
Fun Fact: In 1981 bohrium became the first of six elements discovered by Peter Armbruster and his collaborators at the GSI Helmholtz Institute for Heavy Ion Research, in Darmstadt, Germany.
| Phase | Solid |
| Category | Transition Metals |
| Atomic Weight | [270] |
X
Hs
Hassium
Fun Fact: Researchers in Darmstadt first produced hassium by bombarding lead with iron atoms. Hassium has chemical properties expected of elements in its column—which includes iron—as researchers were able to discern from experiments involving just a handful of atoms.
| Phase | Solid |
| Category | Transition Metals |
| Atomic Weight | [269] |
X
Mt
Meitnerium
Fun Fact: Researchers in Darmstadt named element 109 after Austrian physicist Lise Meitner, who had discovered nuclear fission together with Otto Hahn but—presumably because she was a woman—was not included in Hahn's 1944 Nobel Prize in Chemistry. (When Hitler annexed Austria, Meitner had to flee to Sweden because of her Jewish descent.)
| Phase | Solid |
| Category | Transition Metals |
| Atomic Weight | [278] |
X
Ds
Darmstadtium
Fun Fact: This element is named after the German town of Darmstadt, where researchers at the Institute for Heavy Ion Research first synthesized elements 107 to 112.
| Phase | Solid |
| Category | Transition Metals |
| Atomic Weight | [281] |
X
Rg
Roentgenium
Fun Fact: The team in Darmstadt that first synthesized this element named it after Wilhelm Roentgen, the discoverer of x-rays.
| Phase | Unknown |
| Category | Transition Metals |
| Atomic Weight | [281] |
X
Cn
Copernicium
Fun Fact: The last element to have been discovered at the Institute for Heavy Ion Research, copernicium was also the last one to receive an official name. The IUPAC recognized the naming after astronomer Nicolaus Copernicus as well as copernicium's place in the periodic table in February 2010.
X
Uut
Ununtrium
Fun Fact: A team of researchers from Dubna and Lawrence Berkeley announced in 2004 that they had observed element 113 as a decay product of element 115. Researchers at the RIKEN laboratory in Saitama, Japan, also said they had produced it the same year. Once the IUPAC officially confirms its discovery, it will also give the new element its name.
| Phase | Unknown |
| Category | Unknown |
| Atomic Weight | [286] |
X
Fl
Flerovium
Fun Fact: Some nuclear physicists expect that eventually the chemical properties of new elements will stop mimicking those of elements in the same column of the periodic table, because their electrons will orbit fast enough to show a relativistic effect. Indeed, in 2008 controversial data from the JINR in Dubna, Russia, where 114 was discovered, suggested that its chemistry may be closer to that of a noble gas. The IUPAC officially confirmed the discovery of element 114 in June 2011.
X
Uup
Ununpentium
Fun Fact: In 2004 a team of researchers from Dubna and Berkeley first announced they had produced element 115 in 2003. Once the IUPAC officially confirms its discovery, it will also give the new element an official name.
| Phase | Unknown |
| Category | Unknown |
| Atomic Weight | [289] |
X
Lv
Livermorium
Fun Fact: Element 116 was first seen by researchers in Dubna in 2000. The IUPAC officially confirmed the discovery of 116 (as well as of element 114) in June 2011 and named it on May 30, 2012. The element is named after the Lawrence Livermore National Laboratory, which collaborated on the discovery with the Dubna scientists.
| Phase | Solid |
| Category | Metal |
| Atomic Weight | [293] |
X
Uus
Ununseptium
Fun Fact: Ununseptium is the temporary name of the most recent element to have been synthesized: Russian physicists in Dubna were able to produce just six atoms of it in 2009 in a collaboration with Oak Ridge National Laboratory in Tennessee. The two labs, former Cold War rivals, each contributed one of the ingredients to make 117, namely the heavy isotopes calcium 48 and berkelium 249.
| Phase | Unknown |
| Category | Unknown |
| Atomic Weight | [294] |
X
Uuo
Ununoctium
Fun Fact: Lawrence Berkeley Lab had hoped to recapture its primacy in the synthesis of new elements with element 118 and its decay product, 116, but had to retract its claim in 2002 when its own researchers said they had found evidence that Victor Ninov, a member of the team, had fabricated data. In 2006 researchers in Dubna, said they had produced elements 118 and 116—this time for real.
| Phase | Unknown |
| Category | Unknown |
| Atomic Weight | [294] |
X