Compare Elements

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

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Element comparison
Property Cs Cesium Rb Rubidium
Atomic Number 55 higher 37 higher
Symbol Cs different Rb different
Name Cesium different Rubidium different
Atomic Mass 132.9055 higher 85.468 higher
Category Alkali Metals same value Alkali Metals same value
Period 6 higher 5 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 0.79 lower 0.82 lower
Atomic Radius 343 higher 303 higher
Ionization Energy 3.894 lower 4.177 lower
Electron Affinity 0.472 higher 0.468 higher
Oxidation States +1 same value +1 same value
Melting Point 301.59 K (28.44 °C) lower 312.46 K (39.31 °C) lower
Boiling Point 944 K (670.85 °C) lower 961 K (687.85 °C) lower
Density 1.93 higher 1.53 higher
Electron Configuration [Xe]6s1 different [Kr]5s1 different
Year Discovered 1860 different 1861 different

higher lower