Well, this is the new, “approved” name for the series of elements following actinium. IUPAC shifted to this nomenclature in 1986 because the -ide suffix connotes a compound (e.g., sodium chloride, potassium cyanide, etc.), and the actinoids are not compounds. They are elements. In some depictions of the periodic table, these elements are given a special color, to indicate that they are not “merely” metals, but belong to the “special” class of actinoids. They are, nevertheless, metals. They are thus colored as such on this chart. For a virtually identical lecture on this subject, see lanthanoids.
Aluminum, alone of all the metals, retains its color in colloidal groups. All the other metals (except gold) lose their color and appear black at the colloidal level — aluminum retains its color all the way down to the molecular level, and possibly even to the atomic level. No explanation is known for this phenomenon.
This is why some periodic charts show element #104 listed as “Rf” — the symbol for rutherfordium, in honor of Rutherford, and some show the same element as “Kv” — the symbol for kurchatovium, in honor of a Russian researcher by the name of Kurchatov. (IUPAC, by the way, eventually came down in favor of honoring Rutherford. They have also chosen to honor the Dubna laboratory — site of much important work in this field and the Russian equivalent of the Berkeley lab — by naming #105 dubnium.)
Some American workers have proposed naming element #106 Seaborgium, in honor of Glenn Seaborg, a researcher who deserves the honor if anyone ever did. And the priority of this element’s discovery is uncontested. No problem, right? But if Seaborg deserves such an honor, then so does Moseley (who certainly earned the distinction, and to a greater degree even than Mendeleev, who is enshrined at #101). And what about Democritus and Lavoisier and Dalton and Kekule and Becquerel? And why is Einstein among the anointed (element #99)? He wasn’t even a chemist! So who does have the “right” to name an element? And on what grounds?
IUPAC has therefore instituted a system for naming all new elements, by whomever discovered. This is now the official system, although chemists are “permitted” to use “trivial” names if they so desire. So you can keep calling #104 rutherfordium (symbol Rf); #105 dubnium (Db); #106 seaborgium (Sg); #107 bohrium (in honor of Niels Bohr) (and not nielsbohrium, as was once proposed!) (Bh); #108 hassium (Hs); and #109 meitnerium (in honor of Lise Meitner) (Mt) if you want to, but . . .
Officially, new elements (beginning with #104) will be named according to the following scheme. One Latin syllable for each digit, followed by the suffix -ium, indicating that the element is a metal. The Latin syllable meaning zero is nil; one is un; two is bis; three is tri; four is quad; five is pent; six is hex; seven is sept; eight is oct; and nine is enn. Thus, element #104 becomes un (1) - nil (0) - quad (4) - ium (metal), or unnilquadium. Element #105 becomes unnilpentium, #106 is unnilhexium, #107 is unnilseptium, #108 is unniloctium, and #109 is unnilennium. When #110 is discovered, it will be named ununnilium. If element #3287 is ever discovered, it would be called tribisoctseptium. This method covers all possible cases, and, while doing no honor to great scientists, at least offends no one. As such, it has my hearty approval.
On the other hand, a quick trip over to IUPAC’s web site — where I got some of the information in the second, third, and fourth paragraphs in this section — fails to confirm this last paragraph. Hmmmm…
Gold, like all other metals (except aluminum), does not retain its macroscopic color on the colloidal level; unlike the other metals, however, colloidal gold does not appear black. It instead appears ruby, emerald, purple, yellow, and other colors. No explanation for this phenomenon is known.
Well, this is the new, “approved” name for the series of elements following lanthanum. IUPAC shifted to this nomenclature in 1986 because the -ide suffix connotes a compound (e.g., sodium chloride, potassium cyanide, etc.), and the lanthanoids are not compounds. They are elements. In some depictions of the periodic table, these elements are given a special color, to indicate that they are not “merely” metals, but belong to the “special” class of lanthanoids. They are, nevertheless, metals. They are thus colored as such on this chart. For a virtually identical lecture on this subject, see actinoids.