Mendelevium vs Nobelium

Side-by-side comparison of Mendelevium (Md, element 101) and Nobelium (No, element 102) by atomic structure and physical properties.

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PropertyMd Mendelevium No Nobelium
Atomic number101102
SymbolMdNo
NameMendeleviumNobelium
Categoryactinideactinide
Standard Atomic Weight258 u259 u
Period77
GroupN/AN/A
Blockff
Phase at STPSolidSolid
Electron configuration[Rn]5f137s2[Rn]5f147s2
Oxidation states[2, 3][2, 3]
Electronegativity (Pauling)1.31.3
Electron affinity0.98 eV-2.36 eV
Density1.03e+4 kg/m³9900 kg/m³
Melting point826.85 °C826.85 °C
Boiling pointN/AN/A
Discovery year19551957

Key Differences

PropertyMd MendeleviumNo Nobelium
Standard Atomic Weight258 u ↓ lower259 u ↑ higher
Density1.03e+4 kg/m³ ↑ higher9900 kg/m³ ↓ lower
Electron affinity0.98 eV ↑ higher-2.36 eV ↓ lower
Electron configuration[Rn]5f137s2 [Rn]5f147s2
Discovery year1955 1957