Group 9 element
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] These are all transition metals in the d-block.
Group 9 in the periodic table | |||||||||
---|---|---|---|---|---|---|---|---|---|
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↓ Period | |||||||||
4 | 27 Transition metal | ||||||||
5 | 45 Transition metal | ||||||||
6 | 77 Transition metal | ||||||||
7 | Meitnerium (Mt) 109 unknown chemical properties | ||||||||
Legend
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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.
See also
References
- Leigh, G. J. Nomenclature of Inorganic Chemistry: Recommendations 1990. Blackwell Science, 1990. ISBN 0-632-02494-1.