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Periodic table
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neon
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Ne-21
Neon-21 (Ne-21)
Identity
Protons
10
Neutrons
11
Mass number
21
Mass
20.994 ± 0.041 u
Mass excess
-5.732 MeV
Spin
3/2+*
Stability
stable
Natural occurrence
0.270 %
of neon
All isotopes of neon