I’ve wondered occasionally about the patterns in how chemical elements are abbreviated. If you don’t know the abbreviation for an element, is there a simple algorithm that would let you narrow the range of possibilities or improve your odds at guessing?
Here’s a survey of how the elements are abbreviated.
Latin and German
The elements that have been known the longest often have abbreviations that are mnemonic in Latin.
- Iron (Fe)
- Sodium (Na)
- Silver (Ag)
- Tin (Sn)
- Antimony (Sb)
- Tungsten (W)
- Gold (Au)
- Mercury (Hg)
- Lead (Pb)
- Potassium (K)
- Copper (Cu)
I included Tungsten in this section because it also has an abbreviation that is mnemonic in another language, in this case German.
Initial letter
The easiest abbreviations to remember are simply the first letters of the element names (in English).
- Boron (B)
- Carbon (C)
- Fluorine (F)
- Hydrogen (H)
- Iodine (I)
- Nitrogen (N)
- Oxygen (O)
- Phosphorus (P)
- Sulfur (S)
- Uranium (U)
- Vanadium (V)
- Yttrium (Y)
First two letters
The largest group of elements are those abbreviated by the first two letters of their name. When in doubt, guess the first two letters.
- Actinium (Ac)
- Aluminum (Al)
- Americium (Am)
- Argon (Ar)
- Barium (Ba)
- Beryllium (Be)
- Bismuth (Bi)
- Bromine (Br)
- Calcium (Ca)
- Cerium (Ce)
- Chlorine (Cl)
- Cobalt (Co)
- Dysprosium (Dy)
- Erbium (Er)
- Europium (Eu)
- Flerovium (Fl)
- Francium (Fr)
- Gallium (Ga)
- Germanium (Ge)
- Helium (He)
- Holmium (Ho)
- Indium (In)
- Iridium (Ir)
- Krypton (Kr)
- Lanthanum (La)
- Lithium (Li)
- Lutetium (Lu)
- Molybdenum (Mo)
- Neon (Ne)
- Nickel (Ni)
- Nobelium (No)
- Oganesson (Og)
- Osmium (Os)
- Polonium (Po)
- Praseodymium (Pr)
- Radium (Ra)
- Rhodium (Rh)
- Ruthenium (Ru)
- Scandium (Sc)
- Selenium (Se)
- Silicon (Si)
- Tantalum (Ta)
- Tellurium (Te)
- Thorium (Th)
- Titanium (Ti)
- Xenon (Xe)
Many of these elements use the first two letters to avoid a conflict with the first letter. For example, helium uses He because hydrogen already took H.
There are several elements that start with the same letter, and no element uses just the first letter. For example: actinium, aluminum, americium, and argon.
Xenon could have been X, or dysprosium could have been just D, but that’s not how it was done.
First letter and next consonant
The next largest group of elements are abbreviated by their first letter and the next consonant, skipping over a vowel.
- Bohrium (Bh)
- Cadmium (Cd)
- Cesium (Cs)
- Dubnium (Db)
- Gadolinium (Gd)
- Hafnium (Hf)
- Hassium (Hs)
- Livermorium (Lv)
- Magnesium (Mg)
- Manganese (Mn)
- Meitnerium (Mt)
- Neodymium (Nd)
- Neptunium (Np)
- Nihonium (Nh)
- Niobium (Nb)
- Rubidium (Rb)
- Samarium (Sm)
- Technetium (Tc)
- Zinc (Zn)
- Zirconium (Zr)
Many of these elements would cause a conflict if they had been abbreviated using one of the above rules. For example, cadmium could not be C because that’s carbon, and it could not be Ca because that’s calcium.
Initials of first two syllables
- Astatine (At)
- Berkelium (Bk)
- Darmstadtium (Ds)
- Einsteinium (Es)
- Fermium (Fm)
- Lawrencium (Lr)
- Mendelevium (Md)
- Moscovium (Mc)
- Platinum (Pt)
- Promethium (Pm)
- Roentgenium (Rg)
- Terbium (Tb)
- Thallium (Tl)
Initials of first and third syllable
- Californium (Cf)
- Copernicium (Cn)
- Palladium (Pd)
- Rutherfordium (Rf)
- Seaborgium (Sg)
- Tennessine (Ts)
- Ytterbium (Yb)
First and last letter
- Curium (Cm)
- Radon (Rn)
- Thulium (Tm)
Miscellaneous
- Arsenic (As)
- Chromium (Cr)
- Plutonium (Pu)
- Protactinium (Pa)
- Rhenium (Re)
- Strontium (Sr)
Table
Update: Here’s a visualization of the categories above.
Key to the groups above:
- First letter
- First two letters
- First letter and next consonant
- Initials of first and second syllables
- Initials of first and third syllables
- First and last letter
- First letter and something else
- Historical
A couple random facts:
(1) In fact, argon used to be A. Iodine used to be J in German-language publications, and for example Mendeleev has it in his original table.
(2) Tennessine seems like it should be “Tn”, inheriting its abbreviation from Tennessee. But Tn is sometimes used to denote “thoron” (radon-220, so-called because it’s a decay product of thorium).
(3) Plutonium is “Pu” because Seaborg had a juvenile sense of humor; it’s after “pee-you”, the noise one makes when something smells bad. (I suppose you could argue that either Pl or Pt might be confused with platinum.)
Promethium and protactinium both arguably belong in the “Initials of first two syllables” category. That would leave the remaining elements in a “First and third letter” category.
@ Dysprosium could have been D
No, because:
D is for deuterium / 2-hydrogenium, and T for tritium / 3-~
@Nathan
Promethium should be under “initials of first two syllables” as you said. I fixed my mistake after seeing your comment.
Oganesson should be in the “first two letters” list, not the “first letter and next consonant” list.
How about arsenic?
noun
ar·se·nic
First letter of first and second syllable.