This article needs editing to comply with Wikipedia's Manual of Style. (February 2020) |
Part of a series on the |
Periodic table |
---|
There are currently 118 known chemical elements with a wide range of physical and chemical properties. Amongst this diversity, scientists have found it useful to apply names for various sets of elements that have similar properties, to varying degrees. Many of these sets are formally recognized by the standards body IUPAC.[1]
The following collective names are recommended or noted by IUPAC:
Alkali metals | The metals of group 1: Li, Na, K, Rb, Cs, Fr |
Alkaline earth metals | The metals of group 2: Be, Mg, Ca, Sr, Ba, Ra |
Transition elements * | Elements in groups 3 to 11 or 3 to 12 (the latter making up the d-block) |
Pnictogens | The elements of group 15: N, P, As, Sb, Bi † |
Chalcogens | The elements of group 16: O, S, Se, Te, Po † |
Halogens | The elements of group 17: F, Cl, Br, I, At † |
Noble gases | The elements of group 18: He, Ne, Ar, Kr, Xe, Rn † |
Lanthanoids ‡ | Elements 57–71: La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu |
Actinoids ‡ | Elements 89–103: Ac, Th, Pa, U, Np, Pu, Am, Cm, Bk, Cf, Es, Fm, Md, No, Lr |
Rare-earth metals | Sc, Y, plus the lanthanides |
Inner transition elements | f-block elements |
Main group elements | Elements in groups 1–2 or 13–18, excluding hydrogen |
Another common classification is by degree of metallic or nonmetallic behaviour and characteristics. Elements in the vicinity of where the metals and nonmetals meet are sometime classified as metalloids or an equivalent term. These two to three classes are commonly marked by differing background colors in the periodic table.
Many other names for sets of elements are in common use; others have been used throughout history. These sets usually do not aim to cover the whole periodic table (as for example period does), and often overlap or have boundaries that differ between authors. Some examples:
In alphabetic order: