group 9 elements

group 9 elements

cobalt | rhodium | iridium | meitnerium

Periodic table location

Images

| atomic symbol | atomic number | short electronic configuration cobalt | Co | 27 | [Ar]4s^23d^7 rhodium | Rh | 45 | [Kr]5s^14d^8 iridium | Ir | 77 | [Xe]6s^24f^145d^7 meitnerium | Mt | 109 | [Rn]7s^25f^146d^7 | Aufbau diagram | block | group cobalt | 3d 4s | d | 9 rhodium | 4d 5s | d | 9 iridium | 5d 4f 6s | d | 9 meitnerium | 6d 5f 7s | d | 9 | period | atomic mass | half-life cobalt | 4 | 58.933194 u | (stable) rhodium | 5 | 102.9055 u | (stable) iridium | 6 | 192.217 u | (stable) meitnerium | 7 | 278 u | 30 min

phase at STP | all | solid melting point | median | 1964 °C | highest | 2466 °C (iridium) | lowest | 1495 °C (cobalt) | distribution | boiling point | median | 3695 °C | highest | 4428 °C (iridium) | lowest | 2927 °C (cobalt) | distribution | molar heat of fusion | median | 21.7 kJ/mol | highest | 26 kJ/mol (iridium) | lowest | 16.2 kJ/mol (cobalt) | distribution | molar heat of vaporization | median | 495 kJ/mol | highest | 560 kJ/mol (iridium) | lowest | 375 kJ/mol (cobalt) | distribution | specific heat at STP | median | 240 J/(kg K) | highest | 421 J/(kg K) (cobalt) | lowest | 131 J/(kg K) (iridium) | distribution | (properties at standard conditions)

density | median | 12.45 g/cm^3 | highest | 22.56 g/cm^3 (iridium) | lowest | 8.9 g/cm^3 (cobalt) | distribution | liquid density | median | 10.7 g/cm^3 | highest | 19 g/cm^3 (iridium) | lowest | 7.75 g/cm^3 (cobalt) | distribution | molar volume | median | 8.2655 cm^3/mol | highest | 8.52 cm^3/mol (iridium) | lowest | 6.6 cm^3/mol (cobalt) | distribution | Mohs hardness | median | 6 | highest | 6.5 (between microcline and quartz) (iridium) | lowest | 5 (≈ apatite) (cobalt) | distribution | Vickers hardness | all | 1043 MPa | 1246 MPa | 1760 MPa Brinell hardness | all | 700 MPa | 1100 MPa | 1670 MPa bulk modulus | median | 320 GPa | highest | 380 GPa (rhodium) | lowest | 180 GPa (cobalt) | distribution | shear modulus | median | 150 GPa | highest | 210 GPa (iridium) | lowest | 75 GPa (cobalt) | distribution | Young's modulus | median | 275 GPa | highest | 528 GPa (iridium) | lowest | 209 GPa (cobalt) Poisson ratio | all | 0.26 | 0.31 sound speed | median | 4700 m/s | highest | 4825 m/s (iridium) | lowest | 4700 m/s (rhodium) thermal expansion | median | 8.2×10^-6 K^(-1) | highest | 1.3×10^-5 K^(-1) (cobalt) | lowest | 6.4×10^-6 K^(-1) (iridium) | distribution | thermal conductivity | median | 150 W/(m K) | highest | 150 W/(m K) (rhodium and iridium) | lowest | 100 W/(m K) (cobalt) (properties at standard conditions)

resistivity | median | 4.7×10^-8 Ω m (ohm meters) | highest | 6×10^-8 Ω m (ohm meters) (cobalt) | lowest | 4.3×10^-8 Ω m (ohm meters) (rhodium) | distribution | electrical conductivity | median | 2.1×10^7 S/m (siemens per meter) | highest | 2.3×10^7 S/m (siemens per meter) (rhodium) | lowest | 1.7×10^7 S/m (siemens per meter) (cobalt) | distribution | work function | all | 4.98 eV | 5 eV | (5 to 5.76) eV

valence | median | 6 | highest | 6 (rhodium and iridium) | lowest | 4 (cobalt) electronegativity | median | 2.2 | highest | 2.28 (rhodium) | lowest | 1.88 (cobalt) electron affinity | median | 109.7 kJ/mol (kilojoules per mole) | highest | 151 kJ/mol (kilojoules per mole) (iridium) | lowest | 63.7 kJ/mol (kilojoules per mole) (cobalt) | distribution | first ionization energy | median | 760.4 kJ/mol (kilojoules per mole) | highest | 880 kJ/mol (kilojoules per mole) (iridium) | lowest | 719.7 kJ/mol (kilojoules per mole) (rhodium) | distribution |

term symbol | all | ^4F_(9/2) atomic radius | median | 135 pm | highest | 135 pm (3 elements) | lowest | 135 pm (3 elements) covalent radius | median | 141 pm | highest | 142 pm (rhodium) | lowest | 126 pm (cobalt) (electronic ground state properties)