The Mendeleev Periodic Table
This table shows the form of Mendeleev's Periodic Table of the chemical elements as published in 1872. The heading "Reihen" means "Row" and the heading "Gruppe" means "Group". The symbols R2O and RH4, etc., are written in the style of the time which uses superscripts to denote the number of atoms in molecules rather than the current style which uses subscripts. The gaps marked with hyphens ("-") represent chemical elements deduced by Mendeleev as existing but unknown in 1872. He was able to predict with considerable success the properties of some of the missing chemical elements such as germanium.
|8||Cs=133||Ba=137||?Di=138||?Ce=140||-||-||-||- - - -|
|12||-||-||-||Th=231||-||U=240||-||- - - -|
In the standard form of the periodic table the s-block, p-block, and d-block elements are organised into 18 vertical columns called groups. These are labelled from 1 to 18 under current IUPAC numenclature.
Earlier labelling schemes (Trivial Group names)
For historical reasons some Groups have special names. Terms such as the "alkali metals" are in very common use whereas the term "pnictogens" is very much less common. Some of these special names are listed in the Table.
|2||Alakine earth metals|
|8/9/10||Platinum Group Metals|
|18||Noble Gases, Inert Gases|
In addition the elements 57-71 (lanthanum-lutetium) are referred to as the lanthanoids (lanthanides) and the elements 89-103 (actinium-lawrencium) are referred to as the actinoids (actinides). The elements Sc, Y, and the lanthanoids are sometimes referred to as the rare earths.
The s-, p-, and d-blocks contain a total of 18 groups. The latest recommendations from IUPAC (the International Union of Pure and Applied Chemistry) require that these be labelled 1 - 18 from left to right. This is a good recommendation in the sense that it is at least unambiguous.
Confusion in labelling schemes
There are two other ways of labelling the groups, and both use labels 1-8 (often in Roman numeral format) with further A and B labels. Unfortunately there is enormous confusion here. The two schemes are shown in the table below, underneath the new IUPAC scheme in the first row. It is easy to see the origins of the confusion!
One of these systems is more common in America and the other in Europe but there is really only room for one convention on a small planet, which is where the IUPAC systems scores. These days most new books are printed with the IUPAC labels, but often one of the older conventions is given as well.
The point about confusion is important. If you really must use one of the two older formats, then you must define which you are using. Otherwise it's not clear whether Group 3B refers to the boron group or to the scandium group.
Commission on the Nomenclature of Inorganic Chemistry
Recommendations for the Naming of Elements of Atomic Numbers Greater than 100
J. Chatt, Pure Appl. Chem., 1979, 51, 381-384.
The content of this article is Copyright IUPAC.
Recommendations for the Naming of Elements of Atomic Numbers Greater than 100
Elements of atomic numbers of 101 to 103 have trivial names and corresponding two letter symbols approved by IUPAC. The status of these names and symbols is in no way affected by the recommendation of systematic names for elements of atomic numbers greater than 100.
Elements of atomic numbers greater than 103 are often referred to in the scientific literature but receive names only after they have been 'discovered'. Names are needed for indexing and other purposes and the Commission on Nomenclature of Inorganic Chemistry was asked to make recommendations concerning names and symbols of the heavy 'unknown' elements. The Commission decided that these elements would be best named systematically and that names should accord with the following principles:
- The names should be short and obviously related to the atomic numbers of the elements.
- The names should end in 'ium' whether the element was expected to be a metal or otherwise.
- The symbols for the systematically named elements should consist of three letters.
- The symbols should be derived directly from the atomic numbers and be visually related to the names as far as possible.
The reasons for principles (1), (2), and (4) are obvious but those for (3) are not so immediately apparent. The Commission recommends the use of three-letter symbols because any systematically derived set of two-letter symbols will tend to duplicate some of the two-letter symbols of elements of atomic numbers less than 104. Any ad hoc method of removing such duplication will destroy the systematic derivation of the symbol.
The existence of a systematic nomenclature for the unknown elements does not deny the right of 'discoverers' of new elements to suggest other names to the Commission after their discovery has been established beyond all doubt in the general scientific community. For elements 101-103 the systematic names are minor alternatives to the trivial names already approved by IUPAC. The systematic names and symbols for elements of atomic numbers greater than 103 are the only approved names and symbols for those elements until the approval of trivial names by IUPAC.
Nomenclature of Elements of Atomic Numbers greater than 100
- The name is derived directly from the atomic number of the element using the following numerical roots:
- 0 = nil
- 1 = un
- 2 = bi
- 3 = tri
- 4 = quad
- 5 = pent
- 6 = hex
- 7 = sept
- 8 = oct
- 9 = enn
- The roots are put together in the order of the digits which make up the atomic number and terminated by 'ium' to spell out the name. The final 'n' of 'enn' is elided when it occurs before 'nil', and the final 'i' of 'bi' and of 'tri' when it occurs before 'ium'.
- The symbol of the element is composed of the initial letters of the numerical roots which make up the name.
- The root 'un' is pronounced with a long 'u', to rhyme with 'moon'. In the element names each root is to be pronounced separately.
Examples of systematic names
[The original text is altered below to show current or provisional names]
|101||Mendelevium (Unnilunium)||Md (Unu)|
|102||Nobelium (Unnilbium)||No (Unb)|
|103||Lawrencium (Unniltrium)||Lr (Unt)|
|104||Rutherfordium (Unnilquadium)||Rf (Unq)|
|105||Dubnium (Unnilpentium)||Db (Unp)|
|106||Seaborgium (Unnilhexium)||Sg (Unh)|
|107||Bohrium (Unnilseptium)||Bh (Uns)|
|108||Hassium (Unniloctium)||Hs (Uno)|
|109||Meitnerium (Unnilennium)||Mt (Une)|
|110||Darmstadtium (Ununnilium)||Ds (Uun)|
|111||Roentgenium (Unununium)||Rg (Uuu)|
|112||Copernicium (Ununbium)||Cp (Uub)|
Here is a list of the elements sorted by alphabetically by element name.
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