Actinide - Properties

Properties

Actinides have similar properties to lanthanides. The 6d and 7s electronic shells are filled in actinium and thorium, and the 5f shell is being filled with further increase in atomic number; the 4f shell is filled in the lanthanides. The first experimental evidence for the filling of the 5f shell in actinides was obtained by McMillan and Abelson in 1940. As in lanthanides (see lanthanide contraction), the ionic radius of actinides monotonically decreases with atomic number (see also Aufbau principle).

Properties of actinides (the mass of the most long-lived isotope is in square brackets)
Property	Ac	Th	Pa	U	Np	Pu	Am	Cm	Bk	Cf	Es	Fm	Md	No	Lr
Core charge	89	90	91	92	93	94	95	96	97	98	99	100	101	102	103
atomic mass		232.0381	231.03588	238.02891
Number of natural isotopes	3	9	5	9	4	5	5	8	2	5	—	—	—	—	—
Natural isotopes	225, 227–228	226–232, 234–235	231, 233–236	232–240	237–240	238–240, 242, 244	241–245	242–249	249–250	249–253	—	—	—	—	—
Longest-lived isotope	227	232	231	238	237	244	243	247	247	251	252	257	258	259	262
Half-life of the longest-lived isotope	21.8 years	14 billion years	32,500 years	4.47 billion years	2.14 million years	80.8 million years	7,370 years	15.6 million years	1,400 years	900 years	1.29 years	100.5 days	52 days	58 min	261 min
Electronic configuration in the ground state	6d17s2	6d27s2	5f26d17s2or 5f16d27s2	5f36d17s2	5f46d17s2or 5f57s2	5f67s2	5f77s2	5f76d17s2	5f97s2or 5f86d17s2	5f107s2	5f117s2	5f127s2	5f137s2	5f147s2	5f147s27p1
Oxidation state	3	3, 4	3, 4, 5	3, 4, 5, 6	3, 4, 5, 6, 7	3, 4, 5, 6, 7	2, 3, 4	3, 4	3, 4	2, 3	2, 3	2, 3	2, 3	2, 3	3
Metallic radius, nm	0.203	0.180	0.162	0.153	0.150	0.162	0.173	0.174	0.170	0.186	0.186	—	—	—	—
Ionic radius, nm: An4+ An3+	— 0.126	0.114 —	0.104 0.118	0.103 0.118	0.101 0.116	0.100 0.115	0.099 0.114	0.099 0.112	0.097 0.110	0.096 0.109	0.085 0.098	0.084 0.091	0.084 0.090	0.084 0.095	0.083 0.088
Temperature, °C: melting boiling	1050 3300	1750 4800	1572 4400	1130 3800	640 3900	640 3230	1176 2610	1340 —	1050 —	900 —	860 —	1530 —	830 —	830 —	1630 —
Density, g/cm3	10.07	11.78	15.37	19.06	20.25	19.84	11.7	13.51	14.78	15.1	8.84
Standard electrode potential, V: E° (An4+/An0) E° (An3+/An0)	— −2.13	−1.83 —	−1.47 —	−1.38 −1.66	−1.30 −1.79	−1.25 −2.00	−0.90 −2.07	−0.75 −2.06	−0.55 −1.96	−0.59 −1.97	−0.36 −1.98	−0.29 −1.96	— −1.74	— −1.20	- −2.10
Color 4+ 3+	— Colorless	Colorless Blue	Yellow Dark blue	Green Purple	Yellow-green Purple	Brown Violet	Red Rose	Yellow Colorless	Beige Yellow-green	Green Green	— Pink	— —	— —	— —	— —

Approximate colors of actinide ions in aqueous solution
Oxidation state	89	90	91	92	93	94	95	96	97	98	99
+3	Ac3+	Th3+	Pa3+	U3+	Np3+	Pu3+	Am3+	Cm3+	Bk3+	Cf3+	Es3+
+4		Th4+	Pa4+	U4+	Np4+	Pu4+	Am4+	Cm4+	Bk4+	Cf4+
+5			PaO+ 2	UO+ 2	NpO+ 2	PuO+ 2	AmO+ 2
+6				UO2+ 2	NpO2+ 2	PuO2+ 2	AmO2+ 2
+7					NpO3+ 2	PuO3+ 2	5-

Famous quotes containing the word properties:

“A drop of water has the properties of the sea, but cannot exhibit a storm. There is beauty of a concert, as well as of a flute; strength of a host, as well as of a hero.”
—Ralph Waldo Emerson (1803–1882)

“The reason why men enter into society, is the preservation of their property; and the end why they choose and authorize a legislative, is, that there may be laws made, and rules set, as guards and fences to the properties of all the members of the society: to limit the power, and moderate the dominion, of every part and member of the society.”
—John Locke (1632–1704)