Argon vs Californium

PropertyAr ArgonCf Californium
Atomic number1898
SymbolArCf
NameArgonCalifornium
Categorynoble-gasactinide
Standard Atomic Weight39.948 u251 u
Period37
Group18N/A
Blockps
Phase at STPgassolid
Electron configuration[Ne]3s23p6[Rn]7s25f10
Oxidation states[0][2, 3, 4, 5]
Electronegativity (Pauling)N/A1.3
Electron affinity-1 eV-0.5 eV
Density1.7837 kg/m³1.510000e+4 kg/m³
Melting point-189.35 °C899.85 °C
Boiling point-185.85 °C-273.15 °C
Discovery year18941950