Ununhexium

Ununhexium, artificially produced radioactive chemical element; symbol Uuh; at. no. 116; mass number of most stable isotope 292; m.p., b.p., sp. gr., and valence unknown. Situated in Group 16 of the periodic table, it is expected to have properties similar to those of polonium and tellurium.

In 1999 a research team at the Lawrence Berkeley National Laboratory in Calif. bombarded lead-208 atoms with high-energy krypton-86 ions to create, apparently, ununoctium (element 118) atoms. The Uuo-293 isotope that they synthesized emitted an alpha particle to decay into Uuh-289, which has a life-life of about 0.6 millisecond, which then emitted an alpha particle to decay into ununquadium (element 114). Although the Berkeley laboratory retracted its claim for creating ununoctium in 2001, other research teams have since created ununhexium directly. No name has yet been adopted for element 116, which is therefore called ununhexium, from the Latin roots un for one and hex for six, under a convention for neutral temporary names proposed by the International Union of Pure and Applied Chemistry (IUPAC) in 1980.

Ununoctium

Ununoctium (y'nənŏk`tēəm), artificially produced radioactive chemical element; symbol Uuo; at. no. 118. Scientists from the Joint Institute for Nuclear Research in Dubna, Russia, and Lawrence Livermore National Laboratory in California collaborated in the discovery of ununoctium in experiments conducted in 2002 and 2005. They bombarded atoms of californium-249 with ions of calcium-48. Among the products of the bombardments were three atoms of ununoctium-294 (one atom in 2002 and two in 2005), each of which decayed in 0.9 milliseconds into an atom of ununhexium by emitting an alpha particle. No name has yet been adopted for element 118, which is therefore called ununoctium, from the Latin roots un for one and oct for eight, under a convention for neutral temporary names proposed by the International Union of Pure and Applied Chemistry (IUPAC) in 1980.

In 1999 a research team at the Lawrence Berkeley National Laboratory in Calif. bombarded lead-208 atoms with high-energy krypton-86 ions to create what an analysis showed to be three atoms of element 118 with mass number 293 and a half-life of less than a millisecond. In 2001, however, the team retracted its claim to have produced ununoctium after other laboratories failed to reproduce their results and after a reanalysis of the original data did not show the production of element 118. A subsequent investigation suggested that the original finding was the result of fraud on the part of one of the team scientists.

See also synthetic elements; transactinide elements; transuranium elements.

Elements

Element	Symbol	Atomic Number	Atomic Weight1	Melting Point (Degrees Celsius)	Boiling Point (Degrees Celsius)
actinium	Ac	89	227.0278	1050.	3200. ±300
aluminum	Al	13	26.98154	660.37	2467.
americium	Am	95	(243)	1172.	2600.
antimony	Sb	51	121.75	630.74	1750.
argon	Ar	18	39.948	−189.2	−185.7
arsenic	As	33	74.9216	817. (at 28 atmospheres)	613. (sublimates)
astatine	At	85	(210)	302. (est.)	337. (est.)
barium	Ba	56	137.33	725.	1640.
berkelium	Bk	97	(247)	1050.	2590.
beryllium	Be	4	9.01218	1278. ±5	2970.
bismuth	Bi	83	208.9804	271.3	1560. ±5
bohrium	Bh	107	(262)	—	—
boron	B	5	10.81	2300.	2550. (sublimates)
bromine	Br	35	79.904	−7.2	58.78
cadmium	Cd	48	112.41	320.9	765.
calcium	Ca	20	40.08	839. ±2	1484.
californium	Cf	98	(251)	900.	1470.
carbon	C	6	12.011	∼3550.	4827.
cerium	Ce	58	140.12	799.	3426.
cesium	Cs	55	132.9054	28.40	669.3
chlorine	Cl	17	35.453	−100.98	−34.6
chromium	Cr	24	51.996	1857. ±20	2672.
cobalt	Co	27	58.9332	1495.	2870.
copper	Cu	29	63.546	1083.4 ±0.2	2567.
curium	Cm	96	(247)	1340. ±40	3110.
darmstadtium	Ds	110	(271)	—	—
dubnium	Db	105	(262)	—	—
dysprosium	Dy	66	162.50	1412.	2562.
einsteinium	Es	99	(252)	857.	—
erbium	Er	68	167.26	1529.	2863.
europium	Eu	63	151.96	822.	1597.
fermium	Fm	100	(257)	1527.	—
fluorine	F	9	18.998403	−219.62	−188.14
francium	Fr	87	(223)	(27) (est.)	(677) (est.)
gadolinium	Gd	64	157.25	1313. ±1	3266.
gallium	Ga	31	69.72	29.78	2403.
germanium	Ge	32	72.59	937.4	2830.
gold	Au	79	196.9665	1064.43	2808.
hafnium	Hf	72	178.49	2227. ±20	4602.
hassium	Hs	108	(265)	—	—
helium	He	2	4.0026	<−272.2	−268.934
holmium	Ho	67	164.9304	1474.	2425.
hydrogen	H	1	1.00794	−259.14	−252.87
indium	In	49	114.82	156.61	2080.
iodine	I	53	126.9045	113.5	184.35
iridium	Ir	77	192.22	2410.	4130.
iron	Fe	26	55.847	1535.	2750.
krypton	Kr	36	83.80	−156.6	−152.30 ±0.10
lanthanum	La	57	138.9055	921.	3457.
lawrencium	Lr	103	(262)	1627.	—
lead	Pb	82	207.2	327.502	1740.
lithium	Li	3	6.941	180.54	1342.
lutetium	Lu	71	174.967	1663.	3395.
magnesium	Mg	12	24.305	648.8 ±0.5	1090.
manganese	Mn	25	54.9380	1244. ±3	1962.
meitnerium	Mt	109	(266)	—	—
mendelevium	Md	101	(258)	827.	—
mercury	Hg	80	200.59	−38.842	356.58
molybdenum	Mo	42	95.94	2617.	4612.
neodymium	Nd	60	144.24	1021.	3068.
neon	Ne	10	20.179	−248.67	−246.048
neptunium	Np	93	237.0482	640. ±1	3902. (est.)
nickel	Ni	28	58.69	1453.	2732.
niobium	Nb	41	92.9064	2468. ±10	4742.
nitrogen	N	7	14.0067	−209.86	−195.8
nobelium	No	102	(259)	827.	—
osmium	Os	76	190.2	3045. ±30	5027. ±100
oxygen	O	8	15.9994	−218.4	−182.962
palladium	Pd	46	106.42	1554.	2970.
phosphorus	P	15	30.97376	44.1 (white)	280. (white)
platinum	Pt	78	195.08	1772.	3827. ±100
plutonium	Pu	94	(244)	641.	3232.
polonium	Po	84	(209)	254.	962.
potassium	K	19	39.0983	63.25	760.
praseodymium	Pr	59	140.9077	931.	3512.
promethium	Pm	61	(145)	1042	3000. (est.)
protactinium	Pa	91	231.0359	<1600.	4026.
radium	Ra	88	226.0254	700.	1140.
radon	Rn	86	(222)	−71.	−61.8
rhenium	Re	75	186.207	3180.	5627. (est.)
rhodium	Rh	45	102.9055	1966. ±3	3727. ±100
roentgenium	Rg	111	(272)	—	—
rubidium	Rb	37	85.4678	38.89	686.
ruthenium	Ru	44	101.07	2310.	3900.
rutherfordium	Rf	104	(261)	—	—
samarium	Sm	62	150.36	1072. ±5	1791.
scandium	Sc	21	44.9559	1541.	2831.
seaborgium	Sg	106	(266)	—	—
selenium	Se	34	78.96	217.	684.9 ±1.0
silicon	Si	14	28.0855	1410.	2355.
silver	Ag	47	107.8682	961.93	2212.
sodium	Na	11	22.98977	97.81 ±0.03	882.9
strontium	Sr	38	87.62	269.	1384.
sulfur	S	16	32.06	112.8	444.674
tantalum	Ta	73	180.9479	2996.	5425. ±100
technetium	Tc	43	(98)	2200.	4877.
tellurium	Te	52	127.60	449.5 ±0.3	989.8 ±3.8
terbium	Tb	65	158.9254	1356.	3123.
thallium	Tl	81	204.383	303.5	1457. ±10
thorium	Th	90	232.0381	1750.	∼4790.
thulium	Tm	69	168.9342	1545. ±15	1947.
tin	Sn	50	118.69	231.9681	2270.
titanium	Ti	22	47.88	1660. ±10	3287.
tungsten	W	74	183.85	3410. ±20	5660.
ununbium	Uub	112	(285)	—	—
ununhexium	Uuh	116	(292)	—	—
ununoctium	Uuo	118	(294)	—	—
ununpentium	Uup	115	(288)	—	—
ununquadium	Uuq	114	(289)	—	—
ununtrium	Uut	113	(284)	—	—
uranium	U	92	238.0289	1132.3 ±0.8	3818.
vanadium	V	23	50.9415	1890. ±10	3380.
xenon	Xe	54	131.29	−111.9	−107.1 ±3
ytterbium	Yb	70	173.04	819.	1194.
yttrium	Y	39	88.9059	1522. ±8	3338.
zinc	Zn	30	65.38	419.58	907.
zirconium	Zr	40	91.22	1852. ±2	4377.

¹ Parentheses indicate most stable isotope.