Page 60 - Nomenclature of Inorganic Chemistry (IUPAC Recommendations 2005)

IR-3.5 E L E M E N T S

13. S 8 sulfur(oF128) a-sulfur
14. S 8 sulfur(mP48) b-sulfur
15. S 8 sulfur(mP32) g-sulfur

In a f ew cases, the Pearson symbol fails to differentiate between two crystalline allotropes o f
the element. In such an event the space group is added to the parentheses. If this still fails to
distinguish the allotropes, the characteristically different lattice parameters will have to be
cited. An alternative notation involving compound type may also be useful (see Section IR-
4.2.5 and Chapter I R-11).

IR-3.4.5 Solid amorphous modifications and commonly recognized allotropes
of indefinite structure
Solid amorphous modifications and commonly recognized allotropes of indefinite structure
are distinguished by customary descriptors s uch as a G reek letter, names based on physical
properties, or mineral names.

Examples:
1. C n vitreous carbon

2. C n graphitic carbon (carbon in the form of graphite, irrespective of
structural defects)
3. P n red phosphorus [a disordered structure containing parts of
phosphorus(oS8) and parts of tetraphosphorus]
4. As n amorphous arsenic

IR-3.5 E L E M E N T S I N T H E P E R I O D I C T A B L E

The groups of elements in the periodic t able (see inside front c over) a re numbered from 1 t o
18. The elements (except hydrogen) of groups 1, 2 a nd 13–18 are designated as main group
elements and, except i n g roup 18, the first two elements of each main group are termed
typical elements. Optionally, the letters s, p, d a nd f m ay be used to distinguish different
blocks of elements. F or example, the elements of groups 3–12 are the d-block elements.
These elements are also commonly referred to as the transition elements, t hough t he
elements of group 12 are not always included; the f-block elements are sometimes referred
to as the inner transition elements. If appropriate f or a p articular purpose, the various groups
may be named from the first element in each, for example e lements of the boron group
(B, Al, Ga, In, Tl), elements of the titanium group (Ti, Zr, Hf, Rf), etc.
The following collective names for like elements are IUPAC-approved: alkali metals
8
(Li, Na, K, Rb, Cs, Fr), alkaline earth metals ( Be, Mg, Ca, S r, Ba, R a), pnictogens (N, P ,
As, Sb, Bi), chalcogens (O, S, Se, Te, Po), halogens (F, Cl, Br, I, At), noble gases (He, Ne,
Ar, Kr, Xe, Rn), l anthanoids (La, Ce, P r, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu),
rare earth metals ( Sc, Y a nd the lanthanoids) a nd actinoids (Ac, Th, Pa, U, Np, Pu, Am, Cm,
Bk, Cf, Es, Fm, Md, No, Lr).

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