Compare Elements

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

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Element comparison
Property La Lanthanum Pm Promethium
Atomic Number 57 lower 61 lower
Symbol La different Pm different
Name Lanthanum different Promethium different
Atomic Mass 138.9055 lower 144.9128 lower
Category Lanthanides same value Lanthanides same value
Period 6 same value 6 same value
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 1.1 no data — no data
Atomic Radius 240 higher 236 higher
Ionization Energy 5.577 higher 5.55 higher
Electron Affinity 0.5 no data — no data
Oxidation States +3 same value +3 same value
Melting Point 1191 K (917.85 °C) lower 1315 K (1041.85 °C) lower
Boiling Point 3737 K (3463.85 °C) higher 3273 K (2999.85 °C) higher
Density 6.15 lower 7.26 lower
Electron Configuration [Xe]6s2 5d1 different [Xe]6s2 4f5 different
Year Discovered 1839 different 1945 different

higher lower