Compare Elements

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

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

higher lower