Compare Elements

Compare two chemical elements side by side across 19 atomic and physical properties.

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Element comparison
Property Th Thorium Pm Promethium
Atomic Number 90 higher 61 higher
Symbol Th different Pm different
Name Thorium different Promethium different
Atomic Mass 232.038 higher 144.9128 higher
Category Actinides different Lanthanides different
Period 7 higher 6 higher
Group 3 same value 3 same value
Block f-Block same value f-Block same value
Standard State Solid same value Solid same value
Electronegativity 1.3 no data — no data
Atomic Radius 237 higher 236 higher
Ionization Energy 6.08 higher 5.55 higher
Electron Affinity — no data — no data
Oxidation States +4 different +3 different
Melting Point 2023 K (1749.85 °C) higher 1315 K (1041.85 °C) higher
Boiling Point 5061 K (4787.85 °C) higher 3273 K (2999.85 °C) higher
Density 11.72 higher 7.26 higher
Electron Configuration [Rn]7s2 6d2 different [Xe]6s2 4f5 different
Year Discovered 1828 different 1945 different

higher lower