Actinide

15 elements

Radioactive elements with atomic numbers 89-103. They are characterized by the filling of 5f electron orbitals. All actinides are radioactive, with uranium and thorium being the most abundant naturally occurring members.

89 Solid Ac Actinium 227.0 u
MP: — BP: —
90 Solid Th Thorium 232.04 u
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91 Solid Pa Protactinium 231.04 u
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92 Solid U Uranium 238.03 u
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93 Solid Np Neptunium 237.0 u
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94 Solid Pu Plutonium 244.0 u
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95 Solid Am Americium 243.0 u
MP: — BP: —
96 Solid Cm Curium 247.0 u
MP: — BP: —
97 Solid Bk Berkelium 247.0 u
MP: — BP: —
98 Solid Cf Californium 251.0 u
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99 Solid Es Einsteinium 252.0 u
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100 Solid Fm Fermium 257.0 u
MP: — BP: —
101 Solid Md Mendelevium 258.0 u
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102 Solid No Nobelium 259.0 u
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103 Solid Lr Lawrencium 266.0 u
MP: — BP: —

Comparison Table

# Symbol Name Mass (u) Melting Pt Boiling Pt Density Phase
89 Ac Actinium 227.0 — — — Solid
90 Th Thorium 232.04 — — — Solid
91 Pa Protactinium 231.04 — — — Solid
92 U Uranium 238.03 — — — Solid
93 Np Neptunium 237.0 — — — Solid
94 Pu Plutonium 244.0 — — — Solid
95 Am Americium 243.0 — — — Solid
96 Cm Curium 247.0 — — — Solid
97 Bk Berkelium 247.0 — — — Solid
98 Cf Californium 251.0 — — — Solid
99 Es Einsteinium 252.0 — — — Solid
100 Fm Fermium 257.0 — — — Solid
101 Md Mendelevium 258.0 — — — Solid
102 No Nobelium 259.0 — — — Solid
103 Lr Lawrencium 266.0 — — — Solid