Periodic Table#
Reference of the chemical elements with atomic number, symbol, atomic weight, and operator-relevant context (toxicity, radioactivity, strategic / dual-use status). Pairs with Hazardous Materials for transport / response context and Units & Conversions for SI / measurement.
The 118 elements (alphabetical by symbol)#
Symbol |
Z |
Name |
Notes / category |
|---|---|---|---|
Ac |
89 |
Actinium |
radioactive; actinide. |
Ag |
47 |
Silver |
precious; conductive. |
Al |
13 |
Aluminum |
lightweight; abundant. |
Am |
95 |
Americium |
transuranic; smoke detectors. |
Ar |
18 |
Argon |
noble gas; welding shield. |
As |
33 |
Arsenic |
toxic; semiconductor doping. |
At |
85 |
Astatine |
extremely rare radioactive halogen. |
Au |
79 |
Gold |
precious; non-reactive. |
B |
5 |
Boron |
semiconductor doping; nuclear control. |
Ba |
56 |
Barium |
alkaline-earth; X-ray contrast. |
Be |
4 |
Beryllium |
toxic; aerospace alloy. |
Bh |
107 |
Bohrium |
synthetic. |
Bi |
83 |
Bismuth |
low-toxicity heavy metal. |
Bk |
97 |
Berkelium |
synthetic actinide. |
Br |
35 |
Bromine |
halogen; flame retardant. |
C |
6 |
Carbon |
backbone of organic chemistry. |
Ca |
20 |
Calcium |
alkaline-earth; biology. |
Cd |
48 |
Cadmium |
toxic; batteries. |
Ce |
58 |
Cerium |
rare earth; catalysts. |
Cf |
98 |
Californium |
synthetic; neutron source. |
Cl |
17 |
Chlorine |
halogen; disinfectant; CW historical. |
Cm |
96 |
Curium |
synthetic actinide. |
Cn |
112 |
Copernicium |
synthetic. |
Co |
27 |
Cobalt |
magnetic; lithium-battery cathode. |
Cr |
24 |
Chromium |
stainless steel; toxic Cr(VI). |
Cs |
55 |
Caesium |
alkali metal; atomic clocks. |
Cu |
29 |
Copper |
conductive; antimicrobial. |
Db |
105 |
Dubnium |
synthetic. |
Ds |
110 |
Darmstadtium |
synthetic. |
Dy |
66 |
Dysprosium |
rare earth; magnets. |
Er |
68 |
Erbium |
rare earth; fiber amplifiers. |
Es |
99 |
Einsteinium |
synthetic actinide. |
Eu |
63 |
Europium |
rare earth; phosphors. |
F |
9 |
Fluorine |
halogen; UF6 enrichment feedstock. |
Fe |
26 |
Iron |
ubiquitous structural metal. |
Fl |
114 |
Flerovium |
synthetic. |
Fm |
100 |
Fermium |
synthetic actinide. |
Fr |
87 |
Francium |
extremely rare radioactive alkali. |
Ga |
31 |
Gallium |
semiconductor; export-controlled (CN 2024). |
Gd |
64 |
Gadolinium |
rare earth; MRI contrast. |
Ge |
32 |
Germanium |
semiconductor; export-controlled. |
H |
1 |
Hydrogen |
lightest; energy carrier. |
He |
2 |
Helium |
noble; cryogenic; coolant. |
Hf |
72 |
Hafnium |
nuclear control rods. |
Hg |
80 |
Mercury |
toxic liquid metal. |
Ho |
67 |
Holmium |
rare earth. |
Hs |
108 |
Hassium |
synthetic. |
I |
53 |
Iodine |
halogen; disinfectant. |
In |
49 |
Indium |
ITO display coatings. |
Ir |
77 |
Iridium |
dense; corrosion-resistant. |
K |
19 |
Potassium |
alkali metal; biology. |
Kr |
36 |
Krypton |
noble gas; lighting. |
La |
57 |
Lanthanum |
rare earth. |
Li |
3 |
Lithium |
alkali; battery / mood stabiliser. |
Lr |
103 |
Lawrencium |
synthetic. |
Lu |
71 |
Lutetium |
rare earth. |
Lv |
116 |
Livermorium |
synthetic. |
Mc |
115 |
Moscovium |
synthetic. |
Md |
101 |
Mendelevium |
synthetic actinide. |
Mg |
12 |
Magnesium |
alkaline-earth; biology + alloy. |
Mn |
25 |
Manganese |
steel alloy; biology. |
Mo |
42 |
Molybdenum |
alloy + catalyst. |
Mt |
109 |
Meitnerium |
synthetic. |
N |
7 |
Nitrogen |
air majority; fertiliser; explosives. |
Na |
11 |
Sodium |
alkali; salt. |
Nb |
41 |
Niobium |
superconducting. |
Nd |
60 |
Neodymium |
rare earth; strong magnets. |
Ne |
10 |
Neon |
noble; lighting. |
Nh |
113 |
Nihonium |
synthetic. |
Ni |
28 |
Nickel |
alloy; batteries. |
No |
102 |
Nobelium |
synthetic actinide. |
Np |
93 |
Neptunium |
transuranic; reactor by-product. |
O |
8 |
Oxygen |
oxidiser; biology. |
Og |
118 |
Oganesson |
synthetic; heaviest known. |
Os |
76 |
Osmium |
dense; rare. |
P |
15 |
Phosphorus |
fertiliser; nucleic acids; CW. |
Pa |
91 |
Protactinium |
radioactive. |
Pb |
82 |
Lead |
toxic heavy metal; gamma-shielding. |
Pd |
46 |
Palladium |
catalytic converters. |
Pm |
61 |
Promethium |
radioactive lanthanide. |
Po |
84 |
Polonium |
radiotoxic; assassination history. |
Pr |
59 |
Praseodymium |
rare earth. |
Pt |
78 |
Platinum |
catalyst; jewelry. |
Pu |
94 |
Plutonium |
fissile; weapons material. |
Ra |
88 |
Radium |
radioactive; historical luminous paint. |
Rb |
37 |
Rubidium |
alkali metal; lasers. |
Re |
75 |
Rhenium |
very rare; turbine blades. |
Rf |
104 |
Rutherfordium |
synthetic. |
Rg |
111 |
Roentgenium |
synthetic. |
Rh |
45 |
Rhodium |
precious; catalyst. |
Rn |
86 |
Radon |
radioactive noble gas; building hazard. |
Ru |
44 |
Ruthenium |
catalyst. |
S |
16 |
Sulfur |
fertiliser; rubber; CW historical. |
Sb |
51 |
Antimony |
flame retardant; semiconductor. |
Sc |
21 |
Scandium |
aerospace alloy. |
Se |
34 |
Selenium |
semiconductor; biology. |
Sg |
106 |
Seaborgium |
synthetic. |
Si |
14 |
Silicon |
semiconductor. |
Sm |
62 |
Samarium |
rare earth; magnets. |
Sn |
50 |
Tin |
alloy; solder. |
Sr |
38 |
Strontium |
pyrotechnics; biology Sr-90 fallout. |
Ta |
73 |
Tantalum |
capacitors; conflict mineral risk. |
Tb |
65 |
Terbium |
rare earth. |
Tc |
43 |
Technetium |
synthetic; medical imaging. |
Te |
52 |
Tellurium |
semiconductor; alloy. |
Th |
90 |
Thorium |
radioactive; reactor fuel candidate. |
Ti |
22 |
Titanium |
lightweight strong; aerospace + medical. |
Tl |
81 |
Thallium |
extremely toxic. |
Tm |
69 |
Thulium |
rare earth. |
Ts |
117 |
Tennessine |
synthetic. |
U |
92 |
Uranium |
fissile; reactor + weapons. |
V |
23 |
Vanadium |
steel alloy; redox-flow battery. |
W |
74 |
Tungsten |
high melting point; armor-piercing. |
Xe |
54 |
Xenon |
noble gas; ion thrusters. |
Y |
39 |
Yttrium |
rare earth; superconductors. |
Yb |
70 |
Ytterbium |
rare earth. |
Zn |
30 |
Zinc |
galvanising; biology. |
Zr |
40 |
Zirconium |
nuclear cladding. |
Categories#
Group |
Members |
|---|---|
Alkali metals |
Li, Na, K, Rb, Cs, Fr. |
Alkaline earth |
Be, Mg, Ca, Sr, Ba, Ra. |
Halogens |
F, Cl, Br, I, At, Ts. |
Noble gases |
He, Ne, Ar, Kr, Xe, Rn, Og. |
Lanthanides |
La (57) … Lu (71). |
Actinides |
Ac (89) … Lr (103). |
Transition metals |
groups 3-12 (most of the middle of the table). |
Post-transition |
Al, Ga, In, Sn, Tl, Pb, Bi, Po. |
Metalloids |
B, Si, Ge, As, Sb, Te, At. |
Reactive nonmetals |
H, C, N, O, P, S, Se, halogens. |
Strategic / dual-use#
Use |
Elements |
|---|---|
Fissile |
U-235, Pu-239 (production: U-238 → Pu-239 via reactor; Th-232 → U-233 via thorium cycle). |
Fusion fuel |
deuterium (D, ²H), tritium (T, ³H), Li-6. |
PGM (platinum gp) |
Ru, Rh, Pd, Os, Ir, Pt; export-sensitive. |
Rare earths |
Sc, Y + lanthanides; CN dominates supply. |
Conflict minerals |
tantalum (Ta, “coltan”), tin (Sn), tungsten (W), gold (Au), the 3TG list (Dodd-Frank §1502). |
Battery |
Li, Co, Ni, Mn, graphite (C). |
Semiconductor |
Si, Ge, Ga, In; CN export controls 2023+ on Ga, Ge. |
Munitions / armor |
W (penetrators), DU (depleted uranium); Cu (jacketing). |
Chemical weapons |
historical use of Cl, S (mustard), F (sarin/soman/VX precursors); CWC controls. |
Radiological |
Co-60, Cs-137, Ir-192, Po-210, Sr-90, Am-241 (security sources). |
Operator notes#
Health hazards by element family, heavy metals (Pb, Hg, Cd, As, Tl) cumulative toxicity; transition metals (Cr-VI carcinogen); radioisotopes (alpha emitters Po-210 / Pu most-internal-toxic).
Sanctions / export control, Galllium + Germanium (China 2023+ restrictions on US export); HEU + Pu under IAEA safeguards; PGM under various national export rules.
Identification in the field, XRF analyzer (handheld) for elemental composition; LIBS for laser- induced breakdown; gamma spectroscopy for isotopes.
Strategic stockpiles, US has stockpiles for ~40 materials (DPA / NDS); China for rare earths; many countries for petroleum.