Periodic Table/Americium
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95Am243 Da

Americium

Actinide·Period 7·f-block

Radioactive metallic transuranic element, belongs to the actinoids. Ten known isotopes. Am-243 is the most stable isotope, with a half-life of 7.95*10^3 years. Discovered by Glenn T. Seaborg and associates in 1945, it was obtained by bombarding Uranium-238 with alpha particles.

Gallery

A small disc of Am-241 under the microscope.

Bionerd, CC BY 3.0 <https://creativecommons.org/licenses/by/3.0>, via Wikimedia Commons

Bohr model of Americium
Emission spectrum of Americium

Emission spectrum

Physical Propertiesmass · density · phase · crystal

Atomic Mass

243Da

Density

12g/cm³

Phase (STP)

Solid

Melting Point

1449.2K

Boiling Point

—

Molar Heat

—

Crystal Structure

—

Atomic Radiiatomic · covalent · van der Waals

Atomic (Empirical)

175.00pm

Covalent

166.00pm

Van der Waals

244.00pm

Electronic Propertieselectronegativity · ionization · affinity

Electron Configuration

[Rn] 5f7 7s2

Electron Shells

2, 8, 18, 32, 25, 8, 2

Electronegativity

—

Electron Affinity

—

1st Ionization Energy

6.0kJ/mol

Oxidation States

+2, +3, +4, +5, +6, +7

Orbital DiagramAufbau · Hund's rule · Pauli exclusion

↑↓
1s2
↑↓
2s2
↑↓
↑↓
↑↓
2p6
↑↓
3s2
↑↓
↑↓
↑↓
3p6
↑↓
↑↓
↑↓
↑↓
↑↓
3d10
↑↓
4s2
↑↓
↑↓
↑↓
4p6
↑↓
↑↓
↑↓
↑↓
↑↓
4d10
↑↓
↑↓
↑↓
↑↓
↑↓
↑↓
↑↓
4f14
↑↓
5s2
↑↓
↑↓
↑↓
5p6
↑↓
↑↓
↑↓
↑↓
↑↓
5d10
↑↓
6s2
↑↓
↑↓
↑↓
6p6
↑
↑
↑
↑
↑
↑
↑
5f7
↑↓
7s2

Full: 1s2 2s2 2p6 3s2 3p6 3d10 4s2 4p6 4d10 4f14 5s2 5p6 5d10 6s2 6p6 5f7 7s2Short: [Rn] 5f7 7s2

Ionization Energies (95 known)

1st6.0 kJ/mol2nd11.7 kJ/mol3rd21.7 kJ/mol4th36.8 kJ/mol5th50.0 kJ/mol6th67.9 kJ/mol7th95.0 kJ/mol8th110.0 kJ/mol9th125.0 kJ/mol10th141.0 kJ/mol11th163.0 kJ/mol12th184.0 kJ/mol13th206.0 kJ/mol14th225.0 kJ/mol15th242.0 kJ/mol16th284.0 kJ/mol17th305.0 kJ/mol18th424.0 kJ/mol19th451.0 kJ/mol20th481.0 kJ/mol21th511.0 kJ/mol22th541.0 kJ/mol23th571.0 kJ/mol24th616.0 kJ/mol25th646.0 kJ/mol26th680.0 kJ/mol27th711.0 kJ/mol28th870.0 kJ/mol29th900.0 kJ/mol30th940.0 kJ/mol31th980.0 kJ/mol32th1090.0 kJ/mol33th1130.0 kJ/mol34th1240.0 kJ/mol35th1280.0 kJ/mol36th1410.0 kJ/mol37th1490.0 kJ/mol38th1570.0 kJ/mol39th1650.0 kJ/mol40th1730.0 kJ/mol41th1820.0 kJ/mol42th1900.0 kJ/mol43th1980.0 kJ/mol44th2070.0 kJ/mol45th2160.0 kJ/mol46th2240.0 kJ/mol47th2320.0 kJ/mol48th2410.0 kJ/mol49th2480.0 kJ/mol50th2874.0 kJ/mol51th2946.0 kJ/mol52th3021.0 kJ/mol53th3101.0 kJ/mol54th3178.0 kJ/mol55th3251.0 kJ/mol56th3402.0 kJ/mol57th3479.0 kJ/mol58th3563.0 kJ/mol59th3641.0 kJ/mol60th3956.0 kJ/mol61th4033.0 kJ/mol62th4115.0 kJ/mol63th4191.0 kJ/mol64th4642.0 kJ/mol65th4733.0 kJ/mol66th4960.0 kJ/mol67th5050.0 kJ/mol68th8040.0 kJ/mol69th8210.0 kJ/mol70th8390.0 kJ/mol71th8590.0 kJ/mol72th8770.0 kJ/mol73th8950.0 kJ/mol74th9380.0 kJ/mol75th9560.0 kJ/mol76th9770.0 kJ/mol77th9960.0 kJ/mol78th10490.0 kJ/mol79th10650.0 kJ/mol80th10830.0 kJ/mol81th11000.0 kJ/mol82th12400.0 kJ/mol83th12600.0 kJ/mol84th13000.0 kJ/mol85th13190.0 kJ/mol86th27110.0 kJ/mol87th27550.0 kJ/mol88th28040.0 kJ/mol89th28500.0 kJ/mol90th33700.0 kJ/mol91th34300.0 kJ/mol92th35100.0 kJ/mol93th35549.4 kJ/mol94th139769.5 kJ/mol95th142153.5 kJ/molSuccessive Ionization Energies

Emission Spectrumvisible range · characteristic spectral lines

409
469
Am emission
380nm750nm
408.9 nm(100%)469.0 nm(40%)

Abundanceby mass

Biological Role

Toxic

Radioactive. Used in smoke detectors (Am-241). Alpha emitter.

Discovery

Discovered By

G.T.Seaborg, R.A.James, L.O.Morgan, A.Ghiorso

Named By

—

Year

1945

Nuclear Data

Known Isotopes

27

Stable Isotopes

0

Stable Mass Numbers

None

Isotopes of Am27 known

NuclideZNMass (AMU)Half-lifeDecayJπAbundance
223Am95128223.04584010.0 msα (1%), β⁺9/2-—
224Am95129224.046442Unknownα, SF——
225Am95130225.045508Unknownα, SF9/2-—
247Am95152247.07209223.0 minβ⁻ (1%)5/2—
248Am95153248.075752Unknownβ⁻3+—
249Am95154249.078480Unknownβ⁻5/2—

Click any isotope for its full page with decay chain:

223Am224Am225Am226Am227Am228Am229Am230Am231Am232Am233Am234Am235Am236Am237Am238Am239Am240Am241Am242Am243Am244Am245Am246Am247Am248Am249Am
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