Compare Elements

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

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Element comparison
Property He Helium Rn Radon
Atomic Number 2 lower 86 lower
Symbol He different Rn different
Name Helium different Radon different
Atomic Mass 4.0026 lower 222.0176 lower
Category Noble Gases same value Noble Gases same value
Period 1 lower 6 lower
Group 18 same value 18 same value
Block p-Block same value p-Block same value
Standard State Gas same value Gas same value
Electronegativity — no data — no data
Atomic Radius 140 lower 220 lower
Ionization Energy 24.587 higher 10.745 higher
Electron Affinity — no data — no data
Oxidation States 0 same value 0 same value
Melting Point 0.95 K (-272.2 °C) lower 202 K (-71.15 °C) lower
Boiling Point 4.22 K (-268.93 °C) lower 211.45 K (-61.7 °C) lower
Density 0.0002 lower 0.0097 lower
Electron Configuration 1s2 different [Xe]6s2 4f14 5d10 6p6 different
Year Discovered 1868 different 1900 different

higher lower