Compare Elements

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

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Element comparison
Property Fr Francium K Potassium
Atomic Number 87 higher 19 higher
Symbol Fr different K different
Name Francium different Potassium different
Atomic Mass 223.0197 higher 39.0983 higher
Category Alkali Metals same value Alkali Metals same value
Period 7 higher 4 higher
Group 1 same value 1 same value
Block s-Block same value s-Block same value
Standard State Solid same value Solid same value
Electronegativity 0.7 lower 0.82 lower
Atomic Radius 348 higher 275 higher
Ionization Energy 3.9 lower 4.341 lower
Electron Affinity 0.47 lower 0.501 lower
Oxidation States +1 same value +1 same value
Melting Point 300 K (26.85 °C) lower 336.53 K (63.38 °C) lower
Boiling Point — no data 1032 K (758.85 °C) no data
Density — no data 0.89 no data
Electron Configuration [Rn]7s1 different [Ar]4s1 different
Year Discovered 1939 different 1807 different

higher lower