Group 9 element

Group 9, numbered by IUPAC nomenclature, is a group of chemical element in the periodic table. Members are cobalt (Co), rhodium (Rh), iridium (Ir) and perhaps also the chemically uncharacterized meitnerium (Mt). These are all transition metals in the d-block. All known isotopes of meitnerium are radioactive with short half-lives, and it is not known to occur in nature; only minute quantities have been synthesized in laboratories.

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 in the periodic table
Hydrogen Helium
Lithium Beryllium Boron Carbon Nitrogen Oxygen Fluorine Neon
Sodium Magnesium Aluminium Silicon Phosphorus Sulfur Chlorine Argon
Potassium Calcium Scandium Titanium Vanadium Chromium Manganese Iron Cobalt Nickel Copper Zinc Gallium Germanium Arsenic Selenium Bromine Krypton
Rubidium Strontium Yttrium Zirconium Niobium Molybdenum Technetium Ruthenium Rhodium Palladium Silver Cadmium Indium Tin Antimony Tellurium Iodine Xenon
Caesium Barium Lanthanum Cerium Praseodymium Neodymium Promethium Samarium Europium Gadolinium Terbium Dysprosium Holmium Erbium Thulium Ytterbium Lutetium Hafnium Tantalum Tungsten Rhenium Osmium Iridium Platinum Gold Mercury (element) Thallium Lead Bismuth Polonium Astatine Radon
Francium Radium Actinium Thorium Protactinium Uranium Neptunium Plutonium Americium Curium Berkelium Californium Einsteinium Fermium Mendelevium Nobelium Lawrencium Rutherfordium Dubnium Seaborgium Bohrium Hassium Meitnerium Darmstadtium Roentgenium Copernicium Nihonium Flerovium Moscovium Livermorium Tennessine Oganesson
group 8  group 10
IUPAC group number 9
Name by element cobalt group
CAS group number
(US, pattern A-B-A)
part of VIIIB
old IUPAC number
(Europe, pattern A-B)
part of VIII

↓ Period
Cobalt, electrolytic made, 99,9%
Cobalt (Co)
27 Transition metal
Rhodium, powder, pressed, remelted 99,99%
Rhodium (Rh)
45 Transition metal
Pieces of pure iridium
Iridium (Ir)
77 Transition metal
7 Meitnerium (Mt)
109 unknown chemical properties

primordial element
synthetic element
Atomic number color:


Z Element No. of electrons/shell
27 cobalt 2, 8, 15, 2
45 rhodium 2, 8, 18, 16, 1
77 iridium 2, 8, 18, 32, 15, 2
109 meitnerium 2, 8, 18, 32, 32, 15, 2 (predicted)

Meitnerium has not been isolated in pure form, and its properties have not been conclusively observed; only cobalt, rhodium, and iridium have had their properties experimentally confirmed. All three elements are typical silvery-white transition metals, hard, and have high melting and boiling points.


Cobalt has been discovered in Egyptian and Persian artifacts from before the 2nd millennium BCE. Rhodium was discovered in 1803 when William Hyde Wojopllaston dissolved platinum ore in aqua regia, then neutralized the acid with sodium hydroxide. Wollaston then added ammonium chloride, and dissolved all metals except rhodium and palladium with the nitric acid in the aqua regia. Iridium was discovered in a very similar way in 1804 by Smithson Tennant. Meitnerium was discovered in 1982 by bombarding bismuth-209 with iron-58.


All group 9 elements are relatively rare in the earth's crust, with the most abundant, cobalt, only accounting for 0.0029% of the Earth's crust. Rhodium and iridium are two of the rarest naturally occurring elements in the earth, only found in platinum ores. Meitnerium has only been produced in nuclear reactors and has never been observed in nature nor isolated in pure form.

Biological role

Cobalt is an essential trace nutrient to all animals, found in vitamin B-12. Rhodium, iridium, and meitnerium have no known biological roles.


  • Alloys with other metals, primarily to add corrosion and wear resistance
  • Industrial Catalysts
  • Superalloys
  • Electrical Components

See also


G9, G.IX, G09 or G-9 has several uses including:

Group of Nine, a group of nine European states

G9 (consortium), a name for a group of nine Australian internet providers

G9 (album), the debut album of Gloc-9v

G9, a bipin lamp standard

G9 star, a subclass of G-class stars

Canon PowerShot G9, a digital camera

County Route G9 (California)

Gotha G.IX, a 1918 German bomber aircraft

HMS G9, a British G class submarine and one of eight British submarines lost to "friendly fire" in World War I

HMS Quilliam (G09), a 1941 British Royal Navy Q class destroyer

G9, in internet slang, means "Good night"and also :n

Air Arabia, IATA airline designator

Gaia Online, donation item

Gol Transportes Aéreos (Brazil), IATA airline designator

Group 9 element of the periodic tabled

G09, Sequelae of inflammatory diseases of central nervous system ICD-10 code

Nachtjagdgeschwader 1, from its historic Geschwaderkennung code with the Luftwaffe in World War II

Group 9

Group 9 may refer to:

Group 9 element

Group 9 Rugby League

Index of chemistry articles

Chemistry (from Egyptian kēme (chem), meaning "earth") is the physical science concerned with the composition, structure, and properties of matter, as well as the changes it undergoes during chemical reactions.Below is a list of chemistry-related articles. Chemical compounds are listed separately at list of organic compounds, list of inorganic compounds or list of biomolecules.

Periodic table forms
Sets of elements
See also
Group 9 elements

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