Tungsten

Tungsten, also known as wolfram, is a chemical element with symbol W and atomic number 74. It is a Period 6 element, specifically, its Group 6 member. It is a transition metal, often called a third-row transition metal, which means its d electrons are active in bonding. In compounds or minerals, it is usually found in the +4 or +6 oxidation state.

The word tungsten comes from the Swedish language tung sten, which directly translates to heavy stone. Its name in Swedish is volfram, however, in order to distinguish it from scheelite, which in Swedish is alternatively named tungsten.

A hard, rare metal under standard conditions when uncombined, tungsten is found naturally on Earth only in chemical compounds. It was identified as a new element in 1781, and first isolated as a metal in 1783. Its important ores include wolframite and scheelite. The free element is remarkable for its robustness, especially the fact that it has the highest melting point of all the elements. Its high density is 19.3 times that of water, comparable to that of uranium and gold, and much higher (about 1.7 times) than that of lead. Polycrystalline tungsten is an intrinsically brittle and hard material, making it difficult to work. However, pure single-crystalline tungsten is more ductile, and can be cut with a hard-steel hacksaw.

Tungsten's many alloys have numerous applications, including incandescent light bulb filaments, X-ray tubes (as both the filament and target), electrodes in TIG welding, superalloys, and radiation shielding. Tungsten's hardness and high density give it military applications in penetrating projectiles. Its density used to make it a good way to steal gold (a fact now well known to buyers of gold). Tungsten compounds are also often used as industrial catalysts.

Tungsten is the only metal from the third transition series that is known to occur in biomolecules, where it is used in a few species of bacteria and archaea. It is the heaviest element known to be used by any living organism except uranium. Tungsten interferes with molybdenum and copper metabolism and is somewhat toxic to animal life.

NUCLEAR PROPERTIES

The band of observed isotopes and isomers runs from very neutron rich at ¹⁹²W to very proton rich at ¹⁵⁸W. Above ¹⁹²W, beta-decaying, short-lived isotopes are predicted to the neutron dripline near ²⁵⁰W. Note that ¹⁵⁸W has 84 neutrons, 2 above the closed shell at N = 82, so it is prone to alpha decay. ¹⁵⁷W and lighter isotopes have not been observed, but they are predicted to decay by positron emission or electron capture (possibly accompanied by proton emission).

Isotopes ¹⁸⁵W, ¹⁸⁷W, and all heavier isotopes decay by beta emission. All have half-lives under 1000 sec except for ¹⁸⁵W (75.1 d), ¹⁸⁷W (23.72 h), and ¹⁸⁸W (69.78 d). ¹⁸¹W, ¹⁷⁹W, and all lighter isotopes decay by reducing positive charge. All except ¹⁵⁸W either emit positrons or capture electrons (positive beta decay). Isotopes in the band ¹⁷⁰W to ¹⁵⁸W also have an alpha-decay branch resulting from destabilization against alpha decay occurring in nuclei with neutron counts slightly above 82. [This is the same phenomenon that occurs above N = 126.] Of these light isotopes, ¹⁸¹W has a half-life of 121.2 d; ¹⁷⁸W has a half-life of 21.6 d; and ¹⁷⁹W plus ¹⁷⁷W to ¹⁷⁴W all have half-lives exceeding 1000 sec.

Tungsten has five effectively stable isotopes ¹⁸⁶W. ¹⁸⁴W, ¹⁸³W, ¹⁸²W, and ¹⁸⁰W. All except ¹⁸⁰W, which is known to emit alpha parrticles, are also observationally stable. All except ¹⁸⁰W are also produced by both rapid neutron capture during a supernova or neutron star merger and by infrequent neutron capture (s process) in (second ascent) red giants. Formation of ¹⁸⁰W requires a different process, mainly gamma capture / neutron ejection (sometimes called the g-process). Abundances of all isotopes are roughly the same, except for ¹⁸⁰W, which is some 2 orders of magnitude less abundant than the others.

9-Period Periodic Table of Elements
1	1 H																																																																	2 He
2	3 Li	4 Be																																																																	5 B	6 C	7 N	8 O	9 F	10 Ne
3	11 Na	12 Mg																																																																	13 Al	14 Si	15 P	16 S	17 Cl	18 Ar
4	19 K	20 Ca																																																																	21 Sc	22 Ti	23 V	24 Cr	25 Mn	26 Fe	27 Co	28 Ni	29 Cu	30 Zn	31 Ga	32 Ge	33 As	34 Se	35 Br	36 Kr
5	37 Rb	38 Sr																																																																	39 Y	40 Zr	41 Nb	42 Mo	43 Tc	44 Ru	45 Rh	46 Pd	47 Ag	48 Cd	49 In	50 Sn	51 Sb	52 Te	53 I	54 Xe
6	55 Cs	56 Ba																																																					57 La	58 Ce	59 Pr	60 Nd	61 Pm	62 Sm	63 Eu	64 Gd	65 Tb	66 Dy	67 Ho	68 Er	69 Tm	70 Yb	71 Lu	72 Hf	73 Ta	74 W	75 Re	76 Os	77 Ir	78 Pt	79 Au	80 Hg	81 Tl	82 Pb	83 Bi	84 Po	85 At	86 Rn
7	87 Fr	88 Ra																																																					89 Ac	90 Th	91 Pa	92 U	93 Np	94 Pu	95 Am	96 Cm	97 Bk	98 Cf	99 Es	100 Fm	101 Md	102 No	103 Lr	104 Rf	105 Db	106 Sg	107 Bh	108 Hs	109 Mt	110 Ds	111 Rg	112 Cn	113 Nh	114 Fl	115 Mc	116 Lv	117 Ts	118 Og
8	119 Uue	120 Ubn																															121 Ubu	122 Ubb	123 Ubt	124 Ubq	125 Ubp	126 Ubh	127 Ubs	128 Ubo	129 Ube	130 Utn	131 Utu	132 Utb	133 Utt	134 Utq	135 Utp	136 Uth	137 Uts	138 Uto	139 Ute	140 Uqn	141 Uqu	142 Uqb	143 Uqt	144 Uqq	145 Uqp	146 Uqh	147 Uqs	148 Uqo	149 Uqe	150 Upn	151 Upu	152 Upb	153 Upt	154 Upq	155 Upp	156 Uph	157 Ups	158 Upo	159 Upe	160 Uhn	161 Uhu	162 Uhb	163 Uht	164 Uhq	165 Uhp	166 Uhh	167 Uhs	168 Uho	169 Uhe	170 Usn	171 Usu	172 Usb
9	173 Ust	174 Usq
Alkali metal Alkaline earth metal Lanthanide Actinide Superactinide Transition metal Post-transition metal Metalloid Other nonmetal Halogen Noble gas predicted predicted predicted predicted predicted predicted predicted predicted predicted