Group 9 element

Template:Periodic table (group 9) Group 9 is a group (column) of chemical elements in the periodic table. Members are cobalt (Co), rhodium (Rh), iridium (Ir) and meitnerium (Mt).^[1]^{[page needed]} These are all transition metals in the d-block.

Like other groups, the members of this family show patterns in electron configuration, 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.^[1]

In the older group naming systems, this group was combined with group 8 (iron, ruthenium, osmium, 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

Z	Element	No. of electrons per shell	M.P.	B.P.	Year of Discovery	Discoverer
27	cobalt	2, 8, 15, 2	1768 K 1495 °C	3200 K 2927 °C	~1735	Georg Brandt
45	rhodium	2, 8, 18, 16, 1	2237 K 1964 °C	3968 K 3695 °C	1803	W. H. Wollaston
77	iridium	2, 8, 18, 32, 15, 2	2719 K 2446 °C	4403 K 4130 °C	1803	S. Tennant
109	meitnerium	2, 8, 18, 32, 32, 15, 2^[*]	—	—	1982	P. Armbruster and G. Münzenberg

[*] Predicted.

The first three elements are hard silvery-white metals. 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.

References

^ ^a ^b Leigh, G. J. Nomenclature of Inorganic Chemistry: Recommendations 1990. Blackwell Science, 1990. ISBN 0-632-02494-1.

[leigh-1] Leigh, G. J. Nomenclature of Inorganic Chemistry: Recommendations 1990. Blackwell Science, 1990. ISBN 0-632-02494-1.

[1]

Chemistry

See also

References