Transuranium Element

We can think of the atomic numbers of the transuranium elements as mileposts along a Transuranium Highway that begins at uranium (milepost 92) and runs onward into transuranium country as far as milepost 110. As we begin our trip at 92, however, we realize that we are already three mileposts into another series of elements that began back at milepost 89: the actinides. Actinide Road runs from milepost 89 to 103, so it overlaps the middle of our 92-110 transuranium trip. (The road signs between 92 and 103 read both "Actinide Road" and "Transuranium Highway.")

The actinides and all of the transuranium elements fit in periods 6 and 7 on the Periodic Table. The names that go along with the symbols of the elements from 93 to 109 are: Np = neptunium, Pu = plutonium, Am = americium, Cm = curium, Bk = berkelium, Cf = californium, Es = einsteinium, Fm = fermium, Md = mendelevium, No = nobelium, and Lr = lawrencium. Proposed names for elements 104–109 are: Ru = rutherfordium, Db = dubnium, Sg = seaborgium, Bh = bohrium, Hs = hassium, and Mt = meitnerium. Element 110 has not yet been named.

The names of some of the transuranium elements and who discovered them have been the subjects of a raging battle among the world's chemists. In one corner of the name-game ring is the International Union of Pure and Applied Chemistry (IUPAC), a more-or-less official organization that among other things "makes the rules" about how new chemicals should be named. In another corner is the American Chemical Society (ACS) and most of the American and German scientists who discovered transuranium elements. The names listed above are the ACS recommendations.