The periodic table of elements is one of science’s most recognized organizational tools. Many elements, from familiar ones like Magnesium and Aluminum to synthetic ones like Californium and Einsteinium, share the distinct Latin suffix “-ium.” This commonality suggests a fundamental rule in chemical nomenclature, making the exceptions all the more interesting. The elements whose names diverge from the typical “-ium” ending often reflect their long history, unique chemical properties, or specific conventions for naming non-metallic groups.
The Standard Naming Convention
The prevalence of the “-ium” suffix is a direct consequence of the historical practice of naming newly discovered metals. This ending is a Latin neuter suffix applied to the names of metals to denote their nature as a substance. The convention gained momentum in the early 19th century as chemists like Sir Humphry Davy identified new elements, including Sodium and Potassium, consciously adopting the “-ium” ending.
This historical trend has been formalized by the International Union of Pure and Applied Chemistry (IUPAC), the global authority for chemical nomenclature. When scientists synthesize new, often highly unstable, elements, IUPAC’s rules require that their temporary, systematic names end in “-ium.” This systematic approach reinforces the convention, ensuring that the vast majority of the periodic table’s metallic elements adhere to the familiar Latinate ending.
The Total Count of Non-Ium Elements
Among the 118 elements currently recognized, approximately 38 do not end with the “-ium” suffix. This count includes elements whose names conclude with a variety of endings, such as “-on,” “-ine,” “-gen,” or simply a single consonant. This number is relatively small because the majority of known elements, about 95, are categorized as metals, which strongly favor the “-ium” suffix.
The elements that deviate from this naming rule fall into three main categories, reflecting different historical and chemical contexts. These categories include non-metallic elements, elements known since antiquity whose names predate formal conventions, and a few metallic elements ending in the similar but distinct suffix “-um,” such as Platinum and Molybdenum. This non-uniform naming highlights the blend of ancient discovery and modern systematic classification.
Categories of Exceptions to the Naming Rule
Non-Metallic Elements
The most extensive category of exceptions comprises the non-metallic elements found on the right side of the periodic table. Elements like Oxygen, Nitrogen, and Carbon possess names that are deeply rooted in Greek and Latin descriptions of their properties, long before the systematic “-ium” convention was established. Oxygen, for instance, derives its name from the Greek words meaning “acid-former,” while Nitrogen’s name translates to “nitre-former.” These simple, descriptive names were too ingrained in scientific language to be changed.
A specific group of non-metals, the halogens (Group 17), consistently use the suffix “-ine,” as seen in Fluorine, Chlorine, Bromine, and Iodine. Similarly, the noble gases (Group 18) are characterized by the “-on” ending, with examples like Neon, Argon, Krypton, and Xenon. Even the newest, heaviest noble gas, Oganesson, follows this pattern, demonstrating IUPAC’s commitment to retaining chemically meaningful group endings for non-metals.
Elements Known Since Antiquity
Another significant group of exceptions consists of the metals known to early civilizations. These elements, including Iron, Gold, Silver, and Copper, were discovered and named centuries before the advent of modern chemistry. Their common English names do not end in “-ium.”
Their chemical symbols often derive from their original Latin names, which in some cases did use a Latin neuter ending. For example, the symbol for Iron is Fe, from the Latin Ferrum, and Gold is Au, from Aurum. This modern chemical shorthand preserves the ancient linguistic roots that circumvented the later “-ium” rule.