Group 9 of the Periodic Table
Group 9 of the periodic table has 4 elements: Cobalt, Rhodium, Iridium and Meitnerium. Elements in a group have a similar last electron shell, so they show similar chemical properties. Moving down a group, the number of shells and the atomic radius usually increase.
Element list
| Atomic no. | Symbol | Name | Atomic mass | Phase | Short configuration |
|---|---|---|---|---|---|
| 27 | Co | Cobalt | 58.933 | Solid | [Ar] 3d⁷ 4s² |
| 45 | Rh | Rhodium | 102.91 | Solid | [Kr] 4d⁸ 5s¹ |
| 77 | Ir | Iridium | 192.22 | Solid | [Xe] 4f¹⁴ 5d⁷ 6s² |
| 109 | Mt | Meitnerium | 278 | Solid (a theoretical prediction) | [Rn] 5f¹⁴ 6d⁷ 7s² |
Frequently asked questions
What are the group 9 elements of the periodic table?
The group 9 elements are Cobalt (Co), Rhodium (Rh), Iridium (Ir) and Meitnerium (Mt).
How many elements are in group 9?
Group 9 of the periodic table has 4 elements (excluding the lanthanides and actinides).