Period 7

Period 7 is the seventh and bottom row of the periodic table, containing the chemical elements with atomic numbers 87 through 118. It is the second “very long” period, housing 32 elements in total. These include francium (element 87) at the beginning, oganesson (element 118) at the end, and all the elements in between. A defining characteristic of period 7 is that all of its elements are radioactive, meaning they have no stable isotopes. In fact, period 7 encompasses the heaviest naturally occurring radioactive metals as well as numerous synthetic elements that scientists have created in laboratories.

Period 7 notably contains the fifteen actinide elements (from actinium to lawrencium) often shown as a separate row below the main table. These actinides are heavy, mostly man-made metals with very unstable nuclei and diverse chemistry. Elements like thorium and uranium in the actinide series occur in nature in appreciable amounts, but beyond uranium the elements become exceedingly scarce or entirely synthetic. For example, plutonium (element 94) is the last element found in nature in trace quantities; all subsequent elements (95 and above) must be produced artificially in nuclear reactors or particle accelerators. Because these atoms are so large and unstable, their chemical behavior can be quite unusual. Periodic trends that are smooth in lighter periods begin to break down in period 7, influenced by complex relativistic effects in the atoms’ electron structure. Despite these complexities, period 7 completes the known periodic table, culminating in oganesson (element 118), which currently marks the heaviest element ever observed.

To appreciate period 7 as a whole, it helps to see a summary of its elements. Below is a table listing each period 7 element by name, symbol, and atomic number, along with one key use or notable property for each:

Summary of Period 7 Elements (Atomic #87–118)

Atomic No.	Element (Symbol)	Key Use or Notable Property
87	Francium (Fr)	Extremely rare, no commercial uses (highly radioactive)
88	Radium (Ra)	Radioluminescent: emits a faint blue glow in the dark (historically used in glow-in-the-dark paint)
89	Actinium (Ac)	Glows blue due to intense radioactivity; used as a neutron source in research
90	Thorium (Th)	Used in gas lamp mantles (incandescent lanterns); considered as an alternative nuclear fuel
91	Protactinium (Pa)	No significant uses (extremely scarce and toxic); name means “parent of actinium”
92	Uranium (U)	Primary fuel for nuclear power plants and atomic bombs (heaviest element found in large quantities in nature)
93	Neptunium (Np)	First synthetic transuranium element (beyond uranium); a byproduct in nuclear reactors, with no major commercial uses
94	Plutonium (Pu)	Key ingredient in nuclear weapons and some reactor fuels (the Nagasaki bomb used a plutonium core); ^238Pu is used in long-lasting spacecraft batteries (RTGs)
95	Americium (Am)	Used in household smoke detectors (tiny Am-241 sources ionize air to detect smoke)
96	Curium (Cm)	Named after Marie Curie; emits alpha particles and is used in alpha–X-ray spectrometers on Mars rovers to analyze rocks
97	Berkelium (Bk)	Synthetic lab-produced metal (named after Berkeley); no practical uses outside scientific research
98	Californium (Cf)	Powerful neutron emitter: Cf-252 is used as a compact neutron source for materials scanning (e.g. finding gold ores, gauging fuel moisture) and in cancer brachytherapy research
99	Einsteinium (Es)	Discovered in 1952 from debris of the first hydrogen bomb test; highly radioactive, with no practical uses (produced in microgram amounts for research)
100	Fermium (Fm)	Hydrogen-bomb discovery alongside einsteinium; no uses beyond research (can only be made in extreme neutron bombardment conditions)
101	Mendelevium (Md)	First atom-at-a-time element synthesis (1955); named for Dmitri Mendeleev (creator of the periodic table), with no applications outside labs
102	Nobelium (No)	Named after Alfred Nobel; a synthetic element with no practical uses (exists only in experimental settings)
103	Lawrencium (Lr)	Last actinide element; named for Ernest Lawrence (inventor of the cyclotron); no commercial uses, interesting for completing the actinide series
104	Rutherfordium (Rf)	First of the “superheavy” transition metals; named after physicist Ernest Rutherford, but so short-lived that its chemistry is not fully known
105	Dubnium (Db)	Named for Dubna, Russia (site of a major discovery lab); a synthetic element with no practical uses, existing only as a few atoms in experiments
106	Seaborgium (Sg)	Named after Glenn T. Seaborg, a pioneer of transuranium chemistry – notably the first element ever named after a living person at the time of naming; no practical uses (extremely short half-life)
107	Bohrium (Bh)	Honors Niels Bohr (developer of the Bohr atomic model); synthetic and short-lived, with no uses outside research
108	Hassium (Hs)	Named after “Hassia” (Latin for Hesse), the German state of its discovery; only created in labs, no practical applications
109	Meitnerium (Mt)	Named for Lise Meitner, co-discoverer of nuclear fission; a synthetic element with no practical uses
110	Darmstadtium (Ds)	Named after Darmstadt, Germany (where it was synthesized); extremely short-lived, used only for scientific studies of heavy atoms
111	Roentgenium (Rg)	Honors Wilhelm Röntgen (discoverer of X-rays); synthetic, exists only in minute quantities for research
112	Copernicium (Cn)	Named for astronomer Nicolaus Copernicus; predicted to be very volatile – possibly a liquid or gas at room temperature (an unusual property for a metal)
113	Nihonium (Nh)	First element discovered in Asia (Japan); named “Nihon” (Japanese for Japan); extremely short-lived, no uses outside experiments
114	Flerovium (Fl)	Named for physicist Georgy Flerov; experiments show it is highly volatile and perhaps surprisingly inert, possibly the most volatile metal known
115	Moscovium (Mc)	Named for Moscow region (home of the Dubna research lab); synthetic with a half-life of only milliseconds, no practical uses
116	Livermorium (Lv)	Named for Lawrence Livermore National Lab in California (which co-discovered it); another very short-lived superheavy metal with no commercial uses
117	Tennessine (Ts)	Named for Tennessee (location of Oak Ridge National Lab, a discovery site); a superheavy element in the halogen group, though likely metallic in character due to its mass; no practical uses
118	Oganesson (Og)	Named for Yuri Oganessian, a living nuclear physicist; a noble gas that is predicted to be unusually reactive or even solid at room temperature (a “black sheep” of the noble gases)

(Note: All period 7 elements are radioactive and generally have no stable existence in the environment. Uses listed above are specialized or historical; most of these elements are produced only for scientific research.)

The Elements of Period 7

Alkali and Alkaline Earth Metals (Group 1–2)

Francium (Fr, Atomic #87) – The Vanishing Alkali Metal

Main article: Periodic table/Alkali metals/Francium

Francium is an alkali metal and the first element of period 7. It is infamous for being extremely rare and short-lived. In nature it is found only as a transient product of radioactive decay – at any given moment, scientists estimate no more than about 20–30 grams of francium exist in the Earth’s crust! All isotopes of francium decay rapidly (the most stable isotope has a mere 22-minute half-life), so it literally vanishes as quickly as it is formed. Because of this rarity and instability, francium has no practical commercial uses. It was discovered in 1939 by Marguerite Perey in France (hence its name), making it the last element observed in nature rather than synthesized in a lab. Chemically, francium is expected to behave like a heavier cousin of cesium – an extremely reactive metal – but its short life means scientists have not been able to study its chemistry in depth.

Radium (Ra, Atomic #88) – A Glowing Legacy

Main article: Periodic table/Alkaline earth metals/Radium

Radium is a soft, brilliant-white alkaline earth metal that earned fame in the early 20th century for its glowing properties. Freshly isolated radium will luminesce with a pale blue glow in the dark, an eerie light caused by its intense radioactivity. This glow made radium a novelty for use in glow-in-the-dark paints a century ago – most famously on watch dials and instrument panels. In fact, radium’s glow painted the faces of clock dials so they could be read at night, until the health hazards of radiation became apparent (the tragic story of the “Radium Girls” who suffered radiation poisoning underscored these dangers). Radium was discovered by Marie and Pierre Curie in 1898, extracted from uranium ore, and it was one of the first highly radioactive elements studied. All isotopes of radium are unstable; the most long-lived (radium-226) decays over thousands of years, producing radon gas as a byproduct. Today radium has few uses outside of specialized research or historical interest, as safer alternatives have replaced it. Nevertheless, radium’s discovery was pivotal in early nuclear science and it left a legacy (including the unit “rad” for radiation dosage, named after radium).

A 1950s era clock dial painted with radium-based luminescent paint, glowing green after UV exposure. Radium’s radioluminescence made such dials possible, but health risks led to their discontinuation

Actinide Elements (89–103)

Main article: Periodic table/Actinides

The actinides are the 15 elements from actinium (Z=89) to lawrencium (Z=103). They are characterized by the filling of the 5f orbitals and share many chemical similarities, including multiple oxidation states and a tendency to form complex ions. Most are radioactive, with only thorium and uranium occurring naturally in significant amounts, while the others are largely synthetic. Actinides play important roles in nuclear energy and research, but their radioactivity also poses challenges for safe handling and long-term storage.

Transition metals

Rutherfordium (Rf, Atomic #104) – A New Block Begins

Main article: Periodic table/Transition metals/Rutherfordium

Rutherfordium is the first element in period 7 beyond the actinides, falling into the transition metal category of the d-block. It is named after Ernest Rutherford, the New Zealand-born physicist who discovered the nucleus of the atom. The discovery of rutherfordium in the 1960s was hotly debated between a Soviet team in Dubna (who called it “kurchatovium”) and an American team at Lawrence Berkeley (who proposed “rutherfordium”). Eventually, international agreement settled on the name Rutherfordium. This element has an atomic number of 104 and behaves as a heavier homolog to hafnium and zirconium (group 4 of the periodic table). However, given that only a few atoms of rutherfordium have ever been made at a time (with isotopes that last only seconds), its chemical properties are not fully confirmed. Experimental chemistry with rutherfordium indicates it does form compounds like a typical group 4 metal (e.g. RfCl₄ has been observed), but these experiments are extremely challenging due to the element’s fleeting existence.

Rutherfordium’s significance largely lies in being the gateway to the superheavy elements – it was the first element beyond the actinide series, proving that the periodic table indeed continues. There are no uses for rutherfordium outside of research. It’s created in particle accelerators by colliding lighter nuclei (for instance, bombarding a plutonium or californium target with neon ions). For most people, rutherfordium is known only by its name, which honors a giant of nuclear science. Its successful synthesis and naming also represented a thaw in the naming controversy of the transfermium elements, bridging East-West scientific achievements under one periodic table.

Dubnium (Db, Atomic #105) – Named for a Science City

Main article: Periodic table/Transition metals/Dubnium

Dubnium is a synthetic element named after Dubna, Russia – the location of the Joint Institute for Nuclear Research, where a lot of heavy element research took place. Element 105 was another bone of contention between Soviet and American scientists; the Soviets discovered it around 1968 (naming it “nielsbohrium” initially), and the Americans at Berkeley also synthesized it (suggesting the name “hahnium”). Ultimately “dubnium” was chosen to credit Dubna’s contributions. Dubnium falls in group 5 of the periodic table, beneath tantalum, and it should behave somewhat like tantalum or niobium in theory. Some preliminary chemical experiments done one atom at a time indicate dubnium might form complexes in solution akin to other group 5 elements, but the data are limited.

With a half-life of only a few hours at best (for its most stable isotope, ^268Db), dubnium exists only in the laboratory for brief moments. It has no practical uses—its significance is purely scientific. The creation of dubnium expanded the periodic table and tested the limits of how atoms can be identified. The element’s name highlights the collaborative (and competitive) nature of element discovery; a small town north of Moscow (Dubna) now shares its name with an element. For the general public, dubnium doesn’t impact daily life, but it is a reminder of the human stories (and international cooperation) behind the completion of period 7.

Seaborgium (Sg, Atomic #106) – A Living Honor

Main article: Periodic table/Transition metals/Seaborgium

Seaborgium carries a unique distinction: it was the first element named after a living person (chemist Glenn T. Seaborg) at the time of its naming. Seaborg was a towering figure in actinide chemistry (co-discoverer of plutonium and several other elements), so when element 106 was confirmed in the 1990s, it was named “seaborgium” to honor him – a decision that initially stirred controversy but was ultimately accepted. The element itself was discovered in 1974 by teams in both Dubna and Lawrence Berkeley Laboratory. Seaborgium belongs to group 6, under tungsten in the periodic table. If enough of it could be made, we would expect it to behave somewhat like tungsten or molybdenum. Limited experiments have suggested seaborgium may form a stable hexafluoride gas (SgF₆) and an oxychloride, mirroring chemistry of tungsten (which forms WF₆ and WO₂Cl₂), supporting the notion that periodic trends continue even into element 106.

Seaborgium’s isotopes are extremely short-lived (measured in seconds), so like the other transactinides, it has no practical applications. The main significance of seaborgium is commemorative and scientific. It honors Glenn Seaborg’s legacy in real-time (he reportedly was delighted by this honor, calling it his greatest lifetime achievement). And each experiment with seaborgium helps scientists learn how superheavy atoms might remain chemically consistent with lighter ones or begin to show new effects. In everyday terms, seaborgium is not encountered outside nuclear research facilities, but its naming story brought an interesting human touch to period 7 – connecting an element directly to a living scientist’s name.

Bohrium (Bh, Atomic #107) – In Memory of Bohr

Main article: Periodic table/Transition metals/Bohrium

Bohrium is element 107, named after Niels Bohr, the Danish physicist who pioneered our understanding of atomic structure. Discovered in 1981 by the GSI research facility in Darmstadt, Germany, bohrium was initially known by the placeholder name “unnilseptium” or briefly “nielsbohrium.” Eventually IUPAC agreed on “bohrium.” As a member of group 7 in the periodic table, bohrium would be an analog to rhenium (if enough atoms could be studied to compare). Some theoretical and very small-scale experimental evidence suggests bohrium might behave like a heavier rhenium, possibly forming volatile oxides or halides.

All isotopes of bohrium are extremely short-lived (the longest-lived has a half-life on the order of one minute), meaning we can only produce and detect bohrium one atom at a time in particle accelerators. It has no practical use outside of those experiments. The naming of bohrium helped settle some earlier disputes (it acknowledged Bohr without confusion with “boron,” which some worried about). For the general public, bohrium’s importance lies mostly in its name – immortalizing Niels Bohr in the periodic table – and in the fact that it continues the series of discoveries that confirm the periodic table’s reach. It’s a testament to international scientific progress in the late 20th century that element 107 was successfully created and characterized, however briefly.

Hassium (Hs, Atomic #108) – Element from Hesse

Main article: Periodic table/Transition metals/Hassium

Hassium, element 108, takes its name from the Latin “Hassias” for the German state of Hesse, where it was synthesized (at the GSI in Darmstadt, Hesse). The GSI team first produced hassium in 1984. Fittingly, hassium belongs to group 8, lined up under osmium (which itself is named from a Greek word, but coincidentally osmium’s atomic number is 76 and hassium’s 108 — notice 108 = 76 + 32, a pattern from the 32-element jump of the long period!). Hassium is expected to behave like a heavier osmium, a very dense metal known for forming strong oxides. In fact, one of the few chemical experiments on hassium involved synthesizing a few atoms of hassium tetroxide (HsO₄), analogous to osmium tetroxide. Preliminary results indicated hassium tetroxide is similarly volatile, suggesting hassium indeed shares chemical properties with osmium.

This was a remarkable confirmation that even at element 108, the periodic law still holds – group 8 elements form tetroxides, and hassium followed suit as the most short-lived and heaviest congener. Outside such experiments, hassium has no uses. It decays in mere seconds (hassium-270 is one of its longer-lived isotopes at ~10 seconds half-life). The only reason to create hassium is to study it for the sake of knowledge and to serve as a target or stepping stone to even heavier elements. Naming hassium after a place (Hesse) continued the tradition of recognizing the locales of discovery for these superheavy elements. For most people, hassium is obscure – it’s not something that will ever be seen or used directly – but it represents another brick in the wall of the periodic table’s final row.

Meitnerium (Mt, Atomic #109) – Remembering Lise Meitner

Main article: Periodic table/Transition metals/Meitnerium

Meitnerium is element 109, named in honor of Lise Meitner, the Austrian-Swedish physicist who was instrumental in discovering nuclear fission (but famously did not share in the Nobel Prize for that discovery). The naming of meitnerium in 1997 gave overdue recognition to Meitner’s contributions, and notably, Meitner became one of the first female scientists to be honored with an element name. Meitnerium was first synthesized in 1982 at GSI Darmstadt by bombarding bismuth with iron nuclei. Only a single atom was detected in that initial discovery. Meitnerium is a group 9 element, positioned under iridium in the periodic table. If it had a stable form, we would expect it to resemble a very heavy noble metal with properties akin to iridium or platinum. Of course, with half-lives under one second for its known isotopes, any chemical investigation of meitnerium is exceedingly difficult.

As with other elements in this range, meitnerium’s existence is fleeting – it has no practical applications. Its importance is symbolic and scientific. Symbolically, it honors Lise Meitner, thereby increasing the visibility of women in science on the periodic table. Scientifically, each confirmation of such elements tests the limits of atomic theory. The creation of meitnerium helped refine techniques for identifying single atoms via their decay chains. While the general public won’t encounter meitnerium, the element’s name may spark curiosity about Lise Meitner’s story and the dramatic discovery of fission. In the grand scheme, meitnerium stands as yet another achievement in completing period 7, showing human ingenuity in reaching atomic numbers once thought impossible to attain.

Darmstadtium (Ds, Atomic #110) – Pride of Darmstadt

Main article: Periodic table/Transition metals/Darmstadtium

Darmstadtium is element 110, named after the city of Darmstadt in Germany, where it was discovered at the GSI laboratory in 1994. By this point in the periodic table, naming elements after the place of discovery had become a common practice. Darmstadtium is in group 10, which suggests it would behave similarly to platinum or palladium if enough of it could be observed. Theoretical calculations predict it to be a noble metal, possibly with interesting electron-shell effects due to relativistic influences. But practically, we have not been able to study any chemistry of darmstadtium because its isotopes have half-lives measured in milliseconds. The most stable known darmstadtium isotope (^281Ds) lasts about 10 seconds, which is a lot for such a heavy element but still very short for chemistry experiments (and that particular isotope is difficult to produce in quantity).

Darmstadtium’s existence has no practical application outside the lab. It’s created by fusing lighter nuclei (in Darmstadt’s case, lead and nickel were used to produce element 110). The discovery of darmstadtium filled another spot in period 7 and demonstrated that the GSI facility had mastered the art of reaching into the superheavy realm. For the people of Darmstadt, having an element named after their city is a point of pride – much as earlier elements honored big cultural names, this one highlights the location of modern discovery. To most, darmstadtium is one more mysterious name at the bottom of the periodic table, but behind it lies the story of international collaboration in science, as the quest to explore these new elements has been a global one.

Roentgenium (Rg, Atomic #111) – Homage to X-Ray Vision

Main article: Periodic table/Transition metals/Roentgenium

Roentgenium, element 111, is named for Wilhelm Conrad Röntgen, the German physicist who discovered X-rays in 1895. The name was chosen in 2004 to honor Röntgen’s profound impact on science and medicine. Roentgenium was first synthesized in 1994 (also at GSI Darmstadt) by bombarding bismuth with nickel nuclei. As a group 11 element, roentgenium falls under the same column as copper, silver, and gold – the coinage metals. If roentgenium were stable enough, one might expect it to be a heavy, perhaps reddish or yellowish metal (extrapolating from copper’s red and gold’s yellow). There have been speculations about its properties – for instance, relativistic effects might make roentgenium’s chemistry quite interesting, possibly giving it more noble-metal character than gold. But with its isotopes lasting only seconds at best, our knowledge is almost entirely theoretical.

No everyday uses exist for roentgenium; producing it requires high-energy collisions in a lab, and only a handful of atoms have ever been observed. Its significance is largely commemorative (celebrating Röntgen) and as another confirmation of the periodic table’s extendability. The discovery of roentgenium added to the late-20th-century series of element finds by the Darmstadt group. For a science enthusiast, the name roentgenium immediately calls X-rays to mind, even though the element itself doesn’t produce X-rays in any practical sense. It’s a good example of how the naming of these heavy elements often serves to connect chemistry with the broader history of science.

Copernicium (Cn, Atomic #112) – A Gaseous Metal?

Main article: Periodic table/Transition metals/Copernicium

Copernicium, element 112, is named after Nicolaus Copernicus, the Renaissance astronomer who formulated the heliocentric model of the solar system. Discovered in 1996 at GSI Darmstadt, it originally had the temporary moniker “ununbium” until the name Copernicium was approved in 2010. Copernicium is a group 12 element, which places it in the same family as zinc, cadmium, and mercury. One of the fascinating predictions about copernicium is that it might be unusually volatile – some calculations even suggest it could be a gas at room temperature. This would be extraordinary, as it would make copernicium the first metal that is gaseous under standard conditions (mercury is a liquid; copernicium might go a step further). The reason lies in copernicium’s electron configuration and strong relativistic effects on its electrons, potentially giving it a closed-shell, noble-gas-like character that doesn’t bond easily. In fact, Copernicium has been likened more to a noble gas than to a typical metal.

Experimentally confirming these properties is extremely difficult because the longest-lived copernicium isotope has a half-life of around 29 seconds. Still, scientists have managed to do some chemistry – for instance, studying how copernicium atoms attach to gold surfaces – and found signs that copernicium is very volatile, consistent with the predictions. As expected, copernicium has no practical applications; it exists only as fleeting atoms in a lab. But its possible gaseous nature makes it a captivating element for chemists. Copernicium’s name fittingly honors Copernicus, bridging astronomy and chemistry. It reminds us that just as Copernicus revolutionized our view of the cosmos, even at the atomic scale there are surprises (like a “metal” that barely acts like one).

Post-Transition Metals and Others (Tl to Rn)

Nihonium (Nh, Atomic #113) – Rising Sun in the Periodic Table

Main article: Periodic table/Boron group/Nihonium

Nihonium is element 113 and holds a special place as the first element discovered in Asia (and indeed the first found outside Europe or the Americas). The name “nihonium” comes from “Nihon,” one way to say “Japan” in Japanese, chosen by the RIKEN team in Japan that confirmed the element’s discovery in 2004–2012. Prior to that, a joint Russia–US team had evidence of 113 via decay of element 115, but credit ultimately went to the Japanese group for clear independent synthesis. Nihonium is in group 13, under boron/aluminum/gallium/etc., which implies it would be a post-transition metal. It likely behaves somewhat like thallium, perhaps showing stable +1 oxidation state chemistry, but possibly with its own twists due to relativistic effects.

Nihonium’s most stable isotope has a half-life of only about 20 seconds, so any chemical experimentation must be done quickly. There have been very preliminary chemical studies suggesting nihonium might have some volatility (maybe forming a volatile halide or elemental form), but results are not yet conclusive. There are no uses for nihonium beyond the excitement of discovery. For Japan, having “nihonium” on the periodic table was a moment of national pride, celebrating their contribution to nuclear science. For the general public, nihonium highlights how the quest for new elements has become a global endeavor. It’s also an example of how these names can reflect cultural heritage: “Nihon” literally means “Land of the Rising Sun,” so the periodic table now includes a poetic nod to Japan within its ranks.

Flerovium (Fl, Atomic #114) – A Potential Island of Stability?

Main article: Periodic table/Carbon group/Flerovium

Flerovium, element 114, is named after Georgy Flerov, a Soviet physicist who was a pioneer in heavy element research (and founder of the lab in Dubna). It was first synthesized in 1998 by the Dubna-Livermore collaboration. Flerovium has attracted a lot of attention due to its position near the center of a predicted “island of stability” for superheavy nuclei. While most flerovium isotopes still decay in seconds or less, they are slightly longer-lived than some of their neighbors, hinting at increased stability. Flerovium is in group 14, beneath lead. Early predictions and some experiments suggest that flerovium might be unusually inert or “noble” for a metal – perhaps even more so than lead. In fact, one experiment indicated flerovium may not interact with gold surfaces as strongly as expected, which could mean it has a sort of “noble gas” like reluctance to bond. Additionally, flerovium is very volatile – it has been observed to pass through a tiny Teflon capillary in tests, implying it forms a gas or volatile compound easily (consistent with being the most volatile metal).

If one could have a macroscopic amount of flerovium, it might be a very heavy, perhaps gaseous or low-boiling element, maybe with properties more like a noble gas or a very inert liquid. This blurring of the line between metals and noble gases at flerovium is a fascinating consequence of the extreme physics in heavy atoms. Of course, like its peers, flerovium has no practical use outside research. It exists only as a few atoms at a time, made by fusing calcium with plutonium. The study of flerovium is ongoing, as scientists try to pin down whether it indeed sits at the peak of an island of stability or how its chemistry operates. Regardless, flerovium’s name immortalizes Flerov, tying the element to the history of Russian nuclear research.

Moscovium (Mc, Atomic #115) – Tribute to Moscow

Main article: Periodic table/Pnictogens/Moscovium

Moscovium is element 115, named after the Moscow region (Moscow Oblast) to honor the Dubna laboratory’s locale and its collaboration with US labs in discovering this element. First announced in 2003 by the Dubna-Livermore team, it was officially confirmed and named in 2016. Moscovium is in group 15, the nitrogen/pnictogen group, where one might expect it to have properties akin to bismuth or perhaps something like a very heavy arsenic. It decays extremely quickly (with a half-life under a second for the isotope that was confirmed), making direct chemical study almost impossible so far. There are theoretical suggestions that Moscovium’s chemistry could feature a +1 or +3 oxidation state, and that it might form stable compounds like McCl or McF₃ if we could produce enough – but these remain predictions.

As with all these superheavy elements, moscovium’s existence is ephemeral, and it has no practical applications. It’s created by fusing calcium-48 with americium-243, a difficult feat achieved with advanced accelerators and detection methods to see the rare decay chains that signal a new element’s creation. The naming of moscovium recognizes the contribution of Russian science (similar to how americium recognized American science, etc.), and it complements its neighbor element 115’s naming after a region as well. For the general audience, moscovium is mostly known through periodic table news: it was part of the set of four new elements that completed the 7th period announced in 2016. Its name and symbol (Mc) sometimes draw a smile, as “Mc” can remind people of certain fast-food chains, but behind it is cutting-edge physics and international cooperation.

Livermorium (Lv, Atomic #116) – California’s Mark on the Table

Main article: Periodic table/Chalcogens/Livermorium

Livermorium, element 116, is named for the Lawrence Livermore National Laboratory in Livermore, California, which co-discovered the element with Dubna. Announced in 2000 and confirmed over the following decade, Livermorium extends the periodic table’s p-block as a member of group 16 (the oxygen/chalcogen family). If one extrapolates the chemistry, livermorium would be a heavy homolog of polonium – possibly a volatile, metallic or metalloid element that could exhibit a +2 or +4 oxidation state. Some calculations even suggest livermorium might behave more like a metal than a true chalcogen, potentially being quite reactive or showing unexpected bonding preferences.

Empirical data on livermorium is scarce because its isotopes have half-lives only on the order of milliseconds. So far, no chemical experiments have been done with livermorium due to those limitations. The only signs of livermorium’s existence are the detection of its decay products when it is formed in a lab (by fusing curium and calcium, for example). With no practical use, livermorium’s importance lies in completing the sequence of element discoveries and testing nuclear stability theories. It lies near the edge of the predicted island of stability, but its observed lifetimes have been relatively short. The naming of livermorium in 2012 honored the Livermore lab’s long-term partnership with Dubna in heavy element research, cementing a trans-Pacific collaboration in the periodic table. For the public, livermorium is yet another tongue-twister at the bottom of the table, but one that carries a bit of local pride for California, just as element 115 does for Moscow.

Tennessine (Ts, Atomic #117) – A New Halogen (Perhaps)

Main article: Periodic table/Halogens/Tennessine

Tennessine is element 117, named after the state of Tennessee in the United States. This name recognizes the contributions of Oak Ridge National Laboratory (in Tennessee) which produced critical target materials for the element’s discovery, as well as Vanderbilt University and the University of Tennessee. Discovered in 2010 by a Russian-American collaboration, Tennessine filled the last gap in period 7 prior to element 118. It falls in group 17, which is the halogen group (home to fluorine, chlorine, etc.), so one might expect it to be a superheavy halogen. However, Tennessine’s chemical behavior may not neatly match its lighter congeners. There are predictions that, unlike gas-phase halogens such as astatine (element 85, which is already more like a metalloid), tennessine might exhibit some metallic character or at least be less reactive than a typical halogen. Its high atomic mass and electron configuration might make it less inclined to form the -1 anion that defines halogens. Some theoretical studies suggest tennessine could have a positive electron affinity but lower than astatine’s, possibly making it not as “hungry” for electrons as a classic halogen.

So far, no chemical experiments have been done with tennessine – only a few atoms have been detected via their decay sequences. The most stable isotope has a half-life of only tens of milliseconds. In terms of usage, tennessine has none outside fundamental research. The naming in 2016 was celebrated in Tennessee; it’s not often that a U.S. state’s name enters the periodic table. In fact, “Tennessine” (with the element suffix -ine like other halogens) emphasizes its place in the halogen column, even if it likely behaves quite atypically. For science enthusiasts, tennessine represents the penultimate element currently known and hints at how chemistry might evolve as we approach the end of the periodic table.

Oganesson (Og, Atomic #118) – The End of the Period (For Now)

Main article: Periodic table/Noble gases/Oganesson

Oganesson is element 118, the last element in period 7 and currently the highest atomic number element that has been discovered. It is named after Yuri Oganessian, a renowned Russian nuclear physicist who led many superheavy element discoveries – notably making Oganesson only the second element (after Seaborgium) to be named after a living scientist. As element 118, Oganesson falls into group 18, which is the noble gases (the family of helium, neon, argon, etc.). However, Oganesson is expected to be a very unusual noble gas. In fact, calculations indicate that Oganesson might not behave like a gas at all under normal conditions, but rather as a solid (or at least a very reactive substance). The reasoning is that its atoms are enormously heavy and the usual inert electron shell structure of lighter noble gases may be disrupted – one study suggested Oganesson’s electrons form a smeared-out “quasi-metallic” cloud, losing the distinct shell structure of a noble gas. Essentially, Oganesson could be more of a “noble solid” than a noble gas. It might also have a tendency to form some compounds or interact more than a noble gas would. In any case, it’s clearly the “black sheep” of the noble gas family, if those predictions are correct.

Experimentally, we have not confirmed these chemical properties because only a handful of Oganesson atoms have ever been made (by colliding californium with calcium) and they decayed in a fraction of a millisecond. So Oganesson’s chemistry remains a theoretical intrigue. The successful synthesis of element 118 in 2002 (confirmed by 2006) by the Dubna-Livermore collaboration was a landmark – it completed the 7th period of the periodic table. For now, there is no element 119 or beyond that has been officially discovered, making Oganesson the full-stop at the end of the table. Oganesson has no applications aside from crowning the periodic table and challenging our understanding of atomic physics. Its name honors Oganessian’s lifelong dedication to pushing the periodic table’s limits. If the periodic table were a story, period 7 ends with Oganesson – an element that is simultaneously a noble gas by placement but potentially not very noble in behavior, underscoring the fact that as we reach the extremes of matter, nature continues to surprise us.

Conclusion

Period 7 of the periodic table is a grand finale of elemental discovery – a period that stretches the very concept of what an element can be. From francium and radium, which connect to the classic discoveries of the early 1900s, through the uranium and plutonium that defined the nuclear age, and onward to the ghostly “superheavy” elements like flerovium and oganesson that exist only for instants in laboratories, period 7 is rich with scientific significance. It encompasses elements critical to our technology and history (uranium and plutonium in reactors and weapons, americium in smoke alarms, curium and californium in specialized devices) and elements that are purely the domain of research teams pushing the boundaries of physics and chemistry.

In terms of atomic structure and behavior, period 7 highlights how the simple patterns seen in lighter elements evolve into complex landscapes. The actinides show a remarkable variety of oxidation states and behaviors, while the transactinide elements challenge our ability to even define chemical properties when atoms live only for seconds. Relativistic effects – a consequence of electrons moving at speeds close to light in these heavy atoms – cause gold to be yellow, mercury to be liquid, and flerovium or oganesson to perhaps break the mold of their groups. Period 7 thus teaches us that the periodic table is not just a stagnant chart, but a living document that grows and adapts with new knowledge.

The completion of period 7 (with elements up to 118) is a testament to human curiosity and ingenuity. Each element in this period carries a piece of history: Curie’s glow, Fermi’s experiments, Seaborg’s innovations, cold war rivalries, and international collaborations. The names of these elements read like a hall of fame of science and a map of scientific centers around the world. While most of us will never see or hold a sample of einsteinium or meitnerium (and probably wouldn’t want to, given their radioactivity), we all benefit from the knowledge gained by exploring these extremes. Period 7’s story is ongoing – the search for elements beyond 118 continues, and new experiments may yet reveal unexpected chemistry from these heavyweights. In the meantime, period 7 stands as a remarkable chapter in the book of chemistry, where every element has a tale to tell, from the faint blue glow of radium’s paint to the momentary blink of an oganesson atom vanishing into nothingness.