| 2 |  lanthanum 57 | La | Atomic Mass: 138.90547(7) u A soft, silvery-white rare earth metal, lanthanum is the prototype of the lanthanide series. It is used in camera lenses, as an alloying agent, and in the production of mischmetal for lighter flints. |
| 3 |  promethium 61 | Pm | Atomic Mass: [144.91275(2)] u A radioactive rare earth metal, promethium is the only lanthanide with no stable isotopes. It is extremely rare, with its most common isotope, promethium-145, having a half-life of 17.7 years, and is used in luminous paints and atomic batteries. |
| 4 |  samarium 62 | Sm | Atomic Mass: 150.36(2) u A silvery rare earth metal that is relatively stable in air. Samarium is used in samarium-cobalt magnets, which are strong permanent magnets, and in some specialized glass and ceramics. |
| 5 |  gadolinium 64 | Gd | Atomic Mass: 157.25(3) u A silvery-white rare earth metal with ferromagnetic properties below room temperature. Gadolinium is used in magnetic resonance imaging (MRI) contrast agents, in nuclear reactor shielding, and in some specialized alloys. |
| 6 |  terbium 65 | Tb | Atomic Mass: 158.92535(2) u A silvery-white rare earth metal that is malleable and ductile. Terbium is used in green phosphors for fluorescent lamps and color television tubes, in magnetostrictive alloys, and in fuel cells. |
| 7 |  dysprosium 66 | Dy | Atomic Mass: 162.500(1) u A silvery rare earth metal that is relatively soft and paramagnetic at room temperature. Dysprosium is used in strong permanent magnets, lasers, and in commercial lighting. |
| 8 |  holmium 67 | Ho | Atomic Mass: 164.93033(2) u A relatively soft, silvery-white rare earth metal. Holmium has the highest magnetic moment of any naturally occurring element and is used in some laser applications and as a yellow or red coloring agent in glass. |
| 9 |  erbium 68 | Er | Atomic Mass: 167.259(1) u A soft, malleable, silvery-white rare earth metal that is fairly stable in air. Erbium is used in optical fibers, as a pink colorant in glass and ceramics, and in some medical laser applications. |
| 10 |  thulium 69 | Tm | Atomic Mass: 168.93422(2) u A soft, silvery-grey rare earth metal, thulium is the second least abundant of the lanthanides. It is used in portable X-ray devices and in some solid-state lasers. |
| 11 |  ytterbium 70 | Yb | Atomic Mass: 173.045(10) u A soft, malleable, and ductile silvery-white rare earth metal. Ytterbium is used in stainless steel, in some stress gauges, and in certain types of lasers. |
| 12 |  lutetium 71 | Lu | Atomic Mass: 174.9668(1) u A silvery-white rare earth metal that is relatively stable in air, lutetium is the last element in the lanthanide series. It is used in catalysts for cracking hydrocarbons and in some medical imaging detectors. |
| 13 |  americium 95 | Am | Atomic Mass: [243.06138(2)] u A radioactive actinide metal with a silvery-white luster, americium is primarily used in smoke detectors. It is also a potential fuel for radioisotope thermoelectric generators. |
| 14 |  curium 96 | Cm | Atomic Mass: [247.07035(3)] u A hard, dense, silvery radioactive actinide metal. Curium is primarily used in research and as an alpha particle source for space probes and to power heart pacemakers. |
| 15 |  berkelium 97 | Bk | Atomic Mass: [247.07031(3)] u A synthetic, radioactive actinide metal with a silvery appearance, berkelium has no practical applications outside of scientific research. It is produced in very small quantities in nuclear reactors. |
| 16 |  californium 98 | Cf | Atomic Mass: [251.07959(4)] u A synthetic, radioactive actinide metal, californium is a very strong neutron emitter. It is used in medicine for cancer treatment, in metal detectors for aircraft, and as a neutron source in nuclear reactors. |
| 17 |  einsteinium 99 | Es | Atomic Mass: [252.08298(3)] u A synthetic, highly radioactive actinide metal, einsteinium was discovered in the debris of the first hydrogen bomb explosion. Due to its extreme radioactivity and short half-life, it is used only in scientific research. |
| 18 |  fermium 100 | Fm | Atomic Mass: [257.09511(3)] u A synthetic, highly radioactive actinide metal, fermium is produced in very small quantities in nuclear reactors. It has no known practical applications and is used solely for scientific research. |
| 19 | mendelevium 101 | Md | Atomic Mass: [258.09843(3)] u A synthetic, highly radioactive actinide metal, mendelevium is produced by bombarding einsteinium with alpha particles. It has no known uses outside of fundamental scientific research due to its short half-life. |
| 20 | nobelium 102 | No | Atomic Mass: [259.10096(3)] u A synthetic, highly radioactive actinide metal, nobelium is produced in laboratories through nuclear bombardment. Its short half-life limits its use to scientific research. |
| 21 | lawrencium 103 | Lr | Atomic Mass: [266.12076(5)] u A synthetic, highly radioactive actinide metal, lawrencium is the last element in the actinide series. It is produced in particle accelerators and has no applications beyond basic scientific research. |
| 22 | unbibium hypothetical chemical element with the atomic number 122 |
| 23 | unbihexium hypothetical chemical element with the atomic number 126 |
| 26 | unbiennium hypothetical chemical element with the atomic number 129 |
| 27 | untrinilium hypothetical chemical element with the atomic number 130 |
| 29 | unbiseptium hypothetical chemical element with the atomic number 127 |
| 30 | unbioctium hypothetical chemical element with the atomic number 128 |
| 31 | unbiquadium hypothetical chemical element with the atomic number 124 |
| 32 | unbitrium hypothetical chemical element with the atomic number 123 |
| 33 | untriennium hypothetical chemical element with the atomic number 139 |
| 36 | untriseptium hypothetical chemical element with the atomic number 137 |
| 37 | unquadennium hypothetical chemical element with the atomic number 149 |
| 38 | unquadnilium hypothetical chemical element with the atomic number 140 |
| 39 | unpentbium hypothetical chemical element with the atomic number 152 |
| 40 | unpentnilium hypothetical chemical element with the atomic number 150 |
| 41 | unpentunium hypothetical chemical element with the atomic number 151 |
| 42 | unpenttrium hypothetical chemical element with the atomic number 153 |
| 43 | unquadhexium hypothetical chemical element with the atomic number 146 |
| 45 | unquadoctium hypothetical chemical element with the atomic number 148 |
| 47 | unquadpentium hypothetical chemical element with the atomic number 145 |
| 48 | unquadquadium hypothetical chemical element with the atomic number 144 |
| 50 | unquadunium hypothetical chemical element with the atomic number 141 |
| 51 | untripentium hypothetical chemical element with the atomic number 135 |
| 52 | untriquadium hypothetical chemical element with the atomic number 134 |
| 53 | untritrium hypothetical chemical element with the atomic number 133 |
| 54 | unsepttrium hypothetical chemical element with the atomic number 173 |
| 55 | unseptbium hypothetical chemical element with the atomic number 172 |
| 56 | unhexoctium hypothetical chemical element with the atomic number 168 |
| 57 | unhexseptium hypothetical chemical element with the atomic number 167 |
| 59 | unhexennium hypothetical chemical element with the atomic number 169 |
| 60 | unpentquadium hypothetical chemical element with the atomic number 154 |
| 61 | unpentpentium hypothetical chemical element with the atomic number 155 |
| 62 | unhexquadium hypothetical chemical element with the atomic number 164 |
| 65 | unpentoctium hypothetical chemical element with symbol Upo and atomic number 158 |
| 66 | unhexnilium hypothetical chemical element with symbol Uhn and atomic number 160 |
| 67 | unpentennium hypothetical chemical element with symbol Upe and atomic number 159 |
| 68 | unhexunium hypothetical chemical element with symbol Uhu and atomic number 161 |
| 69 | unhexbium hypothetical chemical element with symbol Uhb and atomic number 162 |
| 70 | unhextrium hypothetical chemical element with symbol Uht and atomic number 163 |
| 72 | unseptnilium hypothetical chemical element with symbol Usn and atomic number 170 |
| 73 | unseptunium hypothetical chemical element with symbol Usu and atomic number 171 |
| 74 | unoctquadium hypothetical chemical element with the atomic number 184 |
| 75 |  europium 63 | Eu | Atomic Mass: 151.964(1) u A soft, silvery rare earth metal, europium is the most reactive of the lanthanides. It is highly valued for its luminescent properties, particularly in red and blue phosphors for televisions and fluorescent lamps, and in anti-counterfeiting features on euro banknotes. |
| 76 |  hydrogen 1 | H | Atomic Mass: 1.008 u The lightest chemical element, hydrogen is the most abundant chemical substance in the universe, essential for water and organic compounds. It is a colorless, odorless, highly flammable diatomic gas. |
| 77 |  helium 2 | He | Atomic Mass: 4.002602(2) u A noble gas, helium is the second lightest element and is colorless, odorless, and non-toxic. It has the lowest boiling point of all elements and is used in cryogenics, for inflating balloons, and as a protective atmosphere for welding. |
| 78 |  lithium 3 | Li | Atomic Mass: 6.94 u The lightest metal, lithium is a soft, silvery-white alkali metal that is highly reactive. It is used in rechargeable batteries, particularly for electric vehicles and portable electronic devices, and in some psychiatric medications. |
| 79 |  beryllium 4 | Be | Atomic Mass: 9.0121831(5) u A lightweight, strong, and brittle alkaline earth metal, beryllium is known for its high melting point and stiffness. It is used in alloys for aerospace components, in X-ray windows, and as a neutron moderator in nuclear reactors. |
| 80 |  boron 5 | B | Atomic Mass: 10.81 u A metalloid with diverse allotropes, boron is a hard, brittle, dark-colored element. It is used in the production of borosilicate glass, ceramics, detergents, and as a doping agent in semiconductors. |
| 81 |  carbon 6 | C | Atomic Mass: 12.011 u A fundamental nonmetal, carbon forms the basis of all known life and is found in various forms like diamond, graphite, and amorphous carbon. It is crucial for organic chemistry, fuels, and materials science. |
| 82 |  nitrogen 7 | N | Atomic Mass: 14.007 u A colorless, odorless diatomic nonmetal gas, nitrogen makes up about 78% of Earth's atmosphere. It is vital for amino acids, proteins, and nucleic acids, and is used in fertilizers, explosives, and as a cryogenic refrigerant. |
| 83 |  oxygen 8 | O | Atomic Mass: 15.999 u A highly reactive nonmetal and the third most abundant element in the universe, oxygen is essential for respiration in most living organisms. It forms about 21% of Earth's atmosphere and is crucial for combustion processes. |
| 84 |  fluorine 9 | F | Atomic Mass: 18.998403163(6) u The most electronegative and reactive chemical element, fluorine is a pale yellow diatomic gas. It is used in fluoridation of water, in refrigerants, and in the production of high-performance plastics like Teflon. |
| 85 |  neon 10 | Ne | Atomic Mass: 20.1797(6) u A noble gas, neon is colorless, odorless, and inert. It produces a distinctive red-orange glow when electrified, commonly used in neon signs and fluorescent lighting. |
| 86 |  sodium 11 | Na | Atomic Mass: 22.98976928(2) u A soft, silvery-white, highly reactive alkali metal, sodium readily tarnishes upon exposure to air. It is an essential electrolyte in the human body and is widely used in streetlights, as a heat exchanger in nuclear reactors, and in the chemical industry. |
| 87 |  magnesium 12 | Mg | Atomic Mass: 24.305 u A light, silvery-white alkaline earth metal, magnesium is strong and has a low density. It is essential for many biological processes and is used in alloys for aircraft, in flares, and in pyrotechnics. |
| 88 |  aluminium metallic chemical element of silvery appearance with symbol Al and atomic number 13 |
| 89 |  silicon 14 | Si | Atomic Mass: 28.085 u A metalloid with semiconductor properties, silicon is the second most abundant element in Earth's crust. It is crucial for computer chips, solar cells, and in the form of silica, a major component of glass and ceramics. |
| 90 |  francium 87 | Fr | Atomic Mass: [223.01973(3)] u A highly radioactive alkali metal, francium is the second most electropositive element and extremely rare. Due to its short half-life (22 minutes for the most stable isotope), it has no practical applications and is primarily used in scientific research. |
| 91 |  phosphorus 15 | P | Atomic Mass: 30.973761998(5) u A highly reactive nonmetal with several allotropes, phosphorus is essential for all living cells as a component of DNA, RNA, and ATP. It is primarily used in fertilizers, detergents, and matches. |
| 92 |  iron 26 | Fe | Atomic Mass: 55.845(2) u A silvery-grey, ductile, and malleable transition metal, iron is the most common element on Earth by mass and a key component of steel. It is essential for blood oxygen transport in living organisms and is fundamental to construction and manufacturing. |
| 93 |  sulfur 16 | S | Atomic Mass: 32.06 u A common nonmetal found in various forms, sulfur is known for its distinctive yellow crystals. It is widely used in the production of sulfuric acid, which is essential for industries like fertilizer, chemical manufacturing, and metallurgy. |
| 94 |  chlorine 17 | Cl | Atomic Mass: 35.45 u A highly reactive halogen and a strong oxidizing agent, chlorine is a yellowish-green gas at room temperature. It is commonly used as a disinfectant for water purification, in the production of plastics like PVC, and in various industrial chemicals. |
| 95 |  argon 18 | Ar | Atomic Mass: 39.948(1) u A noble gas, argon is colorless, odorless, and inert, comprising about 0.93% of Earth's atmosphere. It is frequently used as an inert shielding gas in welding, in incandescent and fluorescent lighting, and for preserving historical documents. |
| 96 |  potassium 19 | K | Atomic Mass: 39.0983(1) u A soft, silvery-white alkali metal, potassium is highly reactive and oxidizes rapidly in air. It is a vital electrolyte for human health and is extensively used in fertilizers, soaps, and industrial chemicals. |
| 97 |  calcium 20 | Ca | Atomic Mass: 40.078(4) u A soft, silvery-white alkaline earth metal, calcium is essential for bones, teeth, and numerous physiological functions in living organisms. It is widely used in cement, mortar, and as a reducing agent in metallurgy. |
| 98 |  lead 82 | Pb | Atomic Mass: 207.2(1) u A heavy, soft, malleable post-transition metal, lead is bluish-white when freshly cut but tarnishes to a dull grey. Historically used in plumbing and paints, its use is now restricted due to its toxicity; it is currently primarily used in batteries and ammunition. |
| 99 |  scandium 21 | Sc | Atomic Mass: 44.955908(5) u A silvery-white rare earth metal, scandium is relatively soft and forms a slightly yellowish or pinkish tint upon air exposure. It is mainly used in alloys for aerospace components, sporting goods, and in some high-intensity discharge lamps. |
| 100 |  titanium 22 | Ti | Atomic Mass: 47.867(1) u A lustrous, silvery transition metal, titanium is known for its high strength-to-weight ratio and excellent corrosion resistance. It is extensively used in aerospace, medical implants, high-performance sports equipment, and in pigments as titanium dioxide. |
| 101 |  vanadium 23 | V | Atomic Mass: 50.9415(1) u A hard, silvery-grey transition metal, vanadium is resistant to corrosion. It is primarily used in steel alloys to increase strength and toughness, particularly in tools, surgical instruments, and jet engines. |
| 102 |  chromium 24 | Cr | Atomic Mass: 51.9961(6) u A steely-grey, lustrous, hard, and corrosion-resistant transition metal, chromium is well-known for its vibrant colored compounds. It is essential for stainless steel production, chrome plating, and in various pigments. |
| 103 |  manganese 25 | Mn | Atomic Mass: 54.938044(3) u A hard, brittle, silvery-grey transition metal, manganese is widely distributed in nature. It is crucial for steel production to improve hardness and strength, and is also used in batteries, ceramics, and as a component in many alloys. |
| 104 |  rhenium 75 | Re | Atomic Mass: 186.207(1) u A silvery-white, heavy transition metal with one of the highest melting points, rhenium is also very dense. It is used in high-temperature superalloys for jet engines, in filaments for mass spectrographs, and as a catalyst. |
| 105 |  cobalt 27 | Co | Atomic Mass: 58.933194(3) u A hard, ferromagnetic transition metal, cobalt has a silvery-blue appearance. It is a key component in superalloys for jet engines, in rechargeable batteries, and in vibrant blue pigments for ceramics and glass. |
| 106 |  tungsten 74 | W | Atomic Mass: 183.84(1) u A rare, hard, silvery-white transition metal with the highest melting point of all elements, tungsten is very dense. It is primarily used in light bulb filaments, electrical contacts, cutting tools, and in high-temperature alloys. |
| 107 |  nickel 28 | Ni | Atomic Mass: 58.6934(4) u A silvery-white, lustrous transition metal with a slight golden tinge, nickel is hard, malleable, and ductile. It is highly valued for its corrosion resistance and is widely used in stainless steel, coins, batteries, and superalloys. |
| 108 |  osmium 76 | Os | Atomic Mass: 190.23(3) u A hard, brittle, bluish-white transition metal of the platinum group, osmium is the densest naturally occurring element. It is used in electrical contacts, fountain pen tips, and in specialized alloys where extreme hardness and durability are required. |
| 109 |  copper 29 | Cu | Atomic Mass: 63.546(3) u A reddish-orange, highly ductile and malleable transition metal, copper is an excellent conductor of electricity and heat. It has been used by humans for thousands of years and is vital for electrical wiring, plumbing, and coinage. |
| 110 |  zinc 30 | Zn | Atomic Mass: 65.38(2) u A bluish-white, brittle metal at room temperature, zinc is widely used as an anti-corrosion coating for steel (galvanizing). It is an essential trace element for human health and is used in batteries, alloys like brass, and various industrial applications. |
| 111 |  gallium 31 | Ga | Atomic Mass: 69.723(1) u A soft, silvery post-transition metal that is solid at room temperature but melts just above it. Gallium is used in high-performance semiconductors, light-emitting diodes (LEDs), and in some medical diagnostic procedures. |
| 112 |  germanium 32 | Ge | Atomic Mass: 72.630(8) u A lustrous, hard, silvery-white metalloid with similar chemical properties to silicon. Germanium is an important semiconductor material used in transistors, solar cells, optical fibers, and infrared optics. |
| 113 |  arsenic 33 | As | Atomic Mass: 74.921595(6) u A poisonous metalloid with several allotropes, arsenic is brittle and can appear grey, yellow, or black. Historically used in pigments and pesticides, its applications are now limited due to its toxicity, though it's still used in some semiconductors and alloys. |
| 114 |  selenium 34 | Se | Atomic Mass: 78.971(8) u A nonmetal with properties intermediate between sulfur and tellurium, selenium exists in various allotropic forms. It is used in electronics (photocells, rectifiers), in glass manufacturing, and as a nutritional supplement. |
| 115 |  iridium 77 | Ir | Atomic Mass: 192.217(3) u A very hard, brittle, silvery-white transition metal of the platinum group, iridium is the most corrosion-resistant metal. It is used in high-temperature equipment, electrical contacts, and as a hardening agent in platinum alloys. |
| 116 |  bromine 35 | Br | Atomic Mass: 79.904 u A reddish-brown volatile liquid at room temperature, bromine is a halogen with a strong, irritating odor. It is used in flame retardants, water purification, agricultural chemicals, and in some pharmaceuticals. |
| 117 |  platinum 78 | Pt | Atomic Mass: 195.084(9) u A dense, malleable, ductile, silvery-white transition metal, platinum is highly valued for its corrosion resistance and catalytic properties. It is extensively used in catalytic converters, jewelry, laboratory equipment, and in dental and medical devices. |
| 118 |  krypton 36 | Kr | Atomic Mass: 83.798(2) u A colorless, odorless noble gas, krypton is known for its use in fluorescent lights and certain types of photographic flashes. It is also employed in some lasers and as a filling gas in energy-efficient windows. |
| 119 |  rubidium 37 | Rb | Atomic Mass: 85.4678(3) u A soft, silvery-white alkali metal that is highly reactive and readily ignites in air. Rubidium has limited commercial uses but is employed in atomic clocks, photocells, and specialized glass. |
| 120 |  gold 79 | Au | Atomic Mass: 196.966570(4) u A dense, soft, malleable, and ductile yellow transition metal, gold is highly valued for its beauty and resistance to corrosion. It has been used as currency, jewelry, and in art for millennia, and is also important in electronics and dentistry. |
| 121 |  mercury 80 | Hg | Atomic Mass: 200.592(3) u A heavy, silvery-white transition metal, mercury is the only metal that is liquid at standard temperature and pressure. It is used in thermometers, barometers, and fluorescent lamps, but its use is declining due to its toxicity. |
| 122 |  thallium 81 | Tl | Atomic Mass: 204.38 u A soft, silvery post-transition metal that resembles tin but tarnishes to a bluish-grey upon exposure to air. Thallium and its compounds are highly toxic, leading to limited uses, primarily in optical lenses and some specialized electronics. |
| 123 |  strontium 38 | Sr | Atomic Mass: 87.62(1) u A soft, silvery-white alkaline earth metal, strontium is highly reactive and quickly turns yellow when exposed to air. It is used in pyrotechnics for a brilliant red color, in signal flares, and in some specialized glass for cathode ray tubes. |
| 124 |  yttrium 39 | Y | Atomic Mass: 88.90584(2) u A silvery-metallic rare earth metal, yttrium is relatively stable in air compared to other rare earths. It is used in alloys to increase strength, in superconductors, in red phosphors for color televisions and displays, and in some medical applications. |
| 125 |  bismuth 83 | Bi | Atomic Mass: 208.98040(1) u A brittle, crystalline post-transition metal with a silvery-pinkish hue, bismuth is the most naturally diamagnetic metal. It is increasingly used as a non-toxic replacement for lead in various applications, including cosmetics, pharmaceuticals, and alloys. |
| 126 |  polonium 84 | Po | Atomic Mass: [208.98243(4)] u A very rare and highly radioactive metalloid, polonium is chemically similar to tellurium and bismuth. It is used as an alpha-particle source in antistatic devices and in some nuclear applications. |
| 127 |  astatine 85 | At | Atomic Mass: [209.98715(5)] u A highly radioactive and rare halogen, astatine is the heaviest known halogen. Its extreme rarity and short half-life limit its study and applications, though some isotopes have potential in targeted alpha therapy for cancer. |
| 128 |  zirconium 40 | Zr | Atomic Mass: 91.224(2) u A lustrous, grayish-white transition metal, zirconium is highly resistant to corrosion. It is primarily used in nuclear reactors due to its low neutron-capture cross-section, in ceramics, and in some medical devices. |
| 129 |  niobium 41 | Nb | Atomic Mass: 92.90637(2) u A lustrous, white, ductile transition metal, niobium is highly resistant to corrosion. It is mainly used in alloys for superconducting magnets, jet engines, and in some specialized steels for structural applications. |
| 130 |  molybdenum 42 | Mo | Atomic Mass: 95.95(1) u A silvery-white, hard transition metal with a very high melting point, molybdenum is valued for its strength and corrosion resistance. It is primarily used in high-strength steel alloys, electrodes, and as a catalyst. |
| 131 |  technetium 43 | Tc | Atomic Mass: [97.90721(3)] u The lightest element with no stable isotopes, technetium is a silvery-grey radioactive transition metal. Its most stable isotope, technetium-99m, is widely used in medical diagnostic imaging. |
| 132 |  ruthenium 44 | Ru | Atomic Mass: 101.07(2) u A rare, hard, silvery-white transition metal of the platinum group, ruthenium is highly resistant to corrosion. It is used as a hardener in platinum and palladium alloys, in electrical contacts, and as a catalyst in various chemical reactions. |
| 133 |  rhodium 45 | Rh | Atomic Mass: 102.90550(2) u A rare, silvery-white, hard transition metal of the platinum group, rhodium is highly reflective and resistant to corrosion. It is primarily used in catalytic converters for automobiles, in jewelry, and in electrical contacts. |
| 134 |  palladium 46 | Pd | Atomic Mass: 106.42(1) u A lustrous, silvery-white transition metal of the platinum group, palladium is highly malleable and ductile. It is extensively used in catalytic converters, jewelry, dentistry, and as a catalyst in chemical synthesis. |
| 135 |  silver 47 | Ag | Atomic Mass: 107.8682(2) u A lustrous, soft, white transition metal, silver is an excellent conductor of electricity and heat. It has been valued for centuries for coinage, jewelry, tableware, and is also used in photography, electronics, and mirrors. |
| 136 |  cadmium 48 | Cd | Atomic Mass: 112.414(4) u A soft, bluish-white metal, cadmium is chemically similar to zinc and mercury. It is used in batteries (NiCd), in pigments for vibrant colors, in low-friction alloys, and as a neutron absorber in nuclear reactors. |
| 137 |  indium 49 | In | Atomic Mass: 114.818(1) u A soft, silvery, malleable post-transition metal, indium is known for its low melting point. It is widely used in indium tin oxide (ITO) coatings for touchscreens and LCDs, in solders, and in some specialized alloys. |
| 138 |  tin 50 | Sn | Atomic Mass: 118.710(7) u A silvery-white, malleable post-transition metal, tin has been used since ancient times, often alloyed with copper to make bronze. It is widely used in solders, coatings for steel (tin cans), and in various alloys. |
| 139 |  uranium 92 | U | Atomic Mass: 238.02891(3) u A dense, silvery-white radioactive actinide metal, uranium is the primary fuel for nuclear reactors and nuclear weapons. It is also used as a counterweight in aircraft and as shielding material. |
| 140 |  antimony 51 | Sb | Atomic Mass: 121.760(1) u A silvery-white metalloid that is brittle and flaky. Antimony is primarily used in flame retardants, in alloys to increase hardness, and in some semiconductor devices. |
| 141 |  tellurium 52 | Te | Atomic Mass: 127.60(3) u A brittle, silvery-white metalloid with properties similar to selenium and sulfur. Tellurium is used in alloys with other metals to improve machinability, in semiconductors, and in solar cells. |
| 142 |  plutonium 94 | Pu | Atomic Mass: [244.06420(3)] u A radioactive actinide metal with a silvery appearance that tarnishes to a dull gray, plutonium is a key fissile material for nuclear weapons and nuclear power. It is highly toxic and radioactive. |
| 143 |  iodine 53 | I | Atomic Mass: 126.90447(3) u A lustrous, dark-gray to purple-black nonmetal solid that sublimes readily into a violet gas, iodine is a halogen. It is an essential trace element for thyroid hormone production and is used as an antiseptic, in photography, and in medicine. |
| 144 |  neptunium 93 | Np | Atomic Mass: [237.04817(3)] u A silvery radioactive actinide metal, neptunium is the first transuranic element. It is produced in nuclear reactors and has some use in neutron detection equipment and as a component in some nuclear weapons. |
| 145 |  xenon 54 | Xe | Atomic Mass: 131.293(6) u A colorless, odorless noble gas, xenon produces a beautiful blue or lavender glow when excited by an electrical discharge. It is used in flash lamps, high-intensity discharge lamps, and in some medical imaging. |
| 146 |  caesium chemical element with symbol Cs and atomic number 55 |
| 147 |  protactinium 89 | Ac | Atomic Mass: [227.02775(3)] u A soft, silvery-white radioactive metal, actinium is the prototype of the actinide series. It is highly radioactive and is used in some radioisotope thermoelectric generators and as a neutron source. |
| 148 |  barium 56 | Ba | Atomic Mass: 137.327(7) u A soft, silvery-white alkaline earth metal, barium is highly reactive. Its compounds are used in various applications, including 'barium meals' for medical imaging, green fireworks, and in the production of vacuum tubes. |
| 149 |  thorium 90 | Th | Atomic Mass: 232.0377(4) u A naturally occurring radioactive actinide metal, thorium is silvery and tarnishes slowly to black. It is a potential nuclear fuel, used in gas mantles, and in some specialized alloys. |
| 150 |  hafnium 72 | Hf | Atomic Mass: 178.49(2) u A lustrous, silvery, ductile transition metal, hafnium is highly corrosion-resistant and chemically similar to zirconium. It is used in nuclear reactor control rods due to its high neutron-absorption cross-section, and in superalloys. |
| 151 |  actinium 89 | Ac | Atomic Mass: [227.02775(3)] u A soft, silvery-white radioactive metal, actinium is the prototype of the actinide series. It is highly radioactive and is used in some radioisotope thermoelectric generators and as a neutron source. |
| 152 |  tantalum 73 | Ta | Atomic Mass: 180.94788(2) u A rare, hard, blue-grey, lustrous transition metal, tantalum is highly corrosion-resistant and has a very high melting point. It is used in electronic components like capacitors, in surgical implants, and in high-temperature alloys. |
| 153 |  radium 88 | Ra | Atomic Mass: [226.02541(3)] u A radioactive alkaline earth metal, radium is silvery-white but readily tarnishes upon exposure to air. Discovered by Marie Curie, it was historically used in luminous paints but its use has declined due to its intense radioactivity and associated health hazards. |
| 154 |  radon 86 | Rn | Atomic Mass: [222.01758(2)] u A radioactive noble gas, radon is colorless, odorless, and tasteless. It is a decay product of uranium and thorium and is a significant indoor air pollutant that poses a health risk due to its radioactivity. |
| 156 | unbinilium hypothetical chemical element with the atomic number 120 |
| 157 | rutherfordium 104 | Rf | Atomic Mass: [267.1218(5)] u A synthetic, highly radioactive transactinide element, rutherfordium is produced in laboratories. It is extremely short-lived and only used for scientific research into its chemical properties. |
| 158 | dubnium 105 | Db | Atomic Mass: [268.1257(5)] u A synthetic, highly radioactive transactinide element, dubnium has a very short half-life. It has no known uses outside of fundamental scientific research. |
| 159 | seaborgium 106 | Sg | Atomic Mass: [269.1286(8)] u A synthetic, highly radioactive transactinide element, seaborgium is produced in particle accelerators. Its fleeting existence limits its study to determining its chemical properties. |
| 160 | bohrium 107 | Bh | Atomic Mass: [270.1333(10)] u A synthetic, highly radioactive transactinide element with a very short half-life. Bohrium is only produced in minute quantities for scientific research. |
| 161 | hassium 108 | Hs | Atomic Mass: [277.1540(10)] u A synthetic, highly radioactive transactinide element with an extremely short half-life. Hassium has no applications beyond its study in nuclear physics and chemistry. |
| 162 | meitnerium 109 | Mt | Atomic Mass: [276.157(10)] u A synthetic, highly radioactive transactinide element, meitnerium is produced in particle accelerators. Its short existence prevents any practical applications, confining it to theoretical and experimental research. |
| 163 | darmstadtium 110 | Ds | Atomic Mass: [281.166(13)] u A synthetic, highly radioactive transactinide element, darmstadtium is produced by nuclear fusion. It has an extremely short half-life, making it useful only for advanced scientific study. |
| 164 | roentgenium 111 | Rg | Atomic Mass: [280.169(15)] u A synthetic, highly radioactive transactinide element, roentgenium is created in laboratories through heavy-ion bombardment. Its very short half-life means it is only used for highly specialized scientific research. |
| 165 | copernicium 112 | Cn | Atomic Mass: [285.177(18)] u A synthetic, highly radioactive transactinide element, copernicium is produced in particle accelerators. It is extremely unstable and its properties are currently a subject of ongoing theoretical and experimental research. |
| 166 | nihonium 113 | Nh | Atomic Mass: [286.182(18)] u A synthetic, highly radioactive superheavy element, nihonium was officially named by IUPAC in 2016. It is extremely unstable and has no practical applications, being solely used for scientific research to understand superheavy elements. |
| 167 | flerovium 114 | Fl | Atomic Mass: [289.190(22)] u A synthetic, highly radioactive superheavy element, flerovium was officially named by IUPAC in 2012. It is extremely unstable, existing only for fractions of a second, and is used solely in scientific research. |
| 168 | moscovium 115 | Mc | Atomic Mass: [289.193(22)] u A synthetic, highly radioactive superheavy element, moscovium was officially named by IUPAC in 2016. Its extreme instability and short half-life mean it has no uses beyond scientific study of superheavy elements. |
| 169 | livermorium 116 | Lv | Atomic Mass: [293.205(25)] u A synthetic, highly radioactive superheavy element, livermorium was officially named by IUPAC in 2012. It is extremely unstable, existing only for milliseconds, and is used for research into nuclear structure. |
| 170 | tennessine 117 | Ts | Atomic Mass: [294.211(26)] u A synthetic, highly radioactive superheavy element, tennessine was officially named by IUPAC in 2016. It is the second-to-last element in the seventh period of the periodic table, with properties of a halogen, and is used only for scientific research. |
| 171 | oganesson 118 | Og | Atomic Mass: [295.216(29)] u A synthetic, highly radioactive superheavy element and a noble gas, oganesson was officially named by IUPAC in 2016. It is the heaviest element discovered to date, with highly unstable isotopes, and is used solely for scientific research into its theoretical properties. |
| 172 |  cerium 58 | Ce | Atomic Mass: 140.116(1) u A soft, silvery, ductile rare earth metal, cerium is the most abundant of the lanthanides. It is used in catalytic converters, self-cleaning ovens, and in glass polishing compounds. |
| 173 |  praseodymium 59 | Pr | Atomic Mass: 140.90766(2) u A soft, silvery, malleable rare earth metal that tarnishes slowly in air. Praseodymium is used to make strong magnets, in carbon arc lighting for studio lights, and in specialty glasses for welding goggles and scientific instruments. |
| 174 |  neodymium 60 | Nd | Atomic Mass: 144.242(3) u A soft, silvery rare earth metal, neodymium is a crucial component in powerful permanent magnets, such as those used in headphones and hard drives. It also gives glass and lasers a purple hue. |
| 175 | Aluminum 13 | Al | Atomic Mass: 26.9815385(7) u A silvery-white, lightweight, and corrosion-resistant post-transition metal, aluminum is the most abundant metal in Earth's crust. It is widely used in transportation, construction, packaging, and electrical applications. |
| 176 | Cesium 55 | Cs | Atomic Mass: 132.90545196(6) u A soft, silvery-gold alkali metal, cesium is the most reactive of all metals and has the lowest electronegativity. It is primarily used in atomic clocks, which define the second, and in specialized photoelectric cells. |