Group 9, by modern
IUPAC numbering, is a group (column) of
chemical elements in the
periodic table
The periodic table, also known as the periodic table of the (chemical) elements, is a rows and columns arrangement of the chemical elements. It is widely used in chemistry, physics, and other sciences, and is generally seen as an icon of ch ...
. Members of Group 9 include
cobalt (Co),
rhodium (Rh),
iridium (Ir) and
meitnerium (Mt).
[Leigh, G. J. ''Nomenclature of Inorganic Chemistry: Recommendations 1990''. Blackwell Science, 1990. .] These are all
transition metals in the
d-block, considered to be some of the most rare of which.
Like other groups, the members of this family show patterns in
electron configuration
In atomic physics and quantum chemistry, the electron configuration is the distribution of electrons of an atom or molecule (or other physical structure) in atomic or molecular orbitals. For example, the electron configuration of the neon atom ...
, especially in the outermost shells, resulting in trends in chemical behavior; however, rhodium deviates from the pattern.
"Group 9" is the modern standard designation for this group, adopted by the
IUPAC in 1990.
[
In the older group naming systems, this group was combined with group 8 ( iron, ruthenium, ]osmium
Osmium (from Greek grc, ὀσμή, osme, smell, label=none) is a chemical element with the symbol Os and atomic number 76. It is a hard, brittle, bluish-white transition metal in the platinum group that is found as a trace element in alloys, mos ...
, and hassium) and group 10 ( nickel, palladium, platinum, and darmstadtium) and called group "VIIIB" in the Chemical Abstracts Service (CAS) "U.S. system", or "VIII" in the old IUPAC (pre-1990) "European system" (and in Mendeleev's original table).
Chemistry
Predicted.
The first three elements are hard silvery-white metals:
Cobalt is a metallic element that can be used to turn glass a deep blue color.
Rhodium can be used in jewelry as a shiny metal.
Iridium is mainly used as a hardening agent for platinum alloys.
All known isotopes of meitnerium are radioactive with short half-lives. Only minute quantities have been synthesized in laboratories. It has not been isolated in pure form, and its physical and chemical properties have not been determined yet.
See also
* Iron group
* Platinum group
References
{{DEFAULTSORT:Group 09
Groups (periodic table)