Tungsten (W)

Introduction

Tungsten is a chemical element with the atomic number 74 in the periodic table. It’s the strongest naturally occurring metal in the world. Element 47 is one of the rarer elements found in Earth’s crust, with an abundance of 1.5 parts per million. 

Being a member of the transition metals family of periodic table elements, this exceptionally strong refractory metal has three valence electrons. It is widely used for its hardness, stability, high melting point, as well as its strong anticorrosive properties. 

Fact Box

Chemical and Physical Properties of Tungsten

The symbol in the periodic table of elements: W

Atomic number: 74

Atomic weight (mass): 183.85 g.mol-1

Group number: 6 (Transition metals)

Period: 6

Color: A lustrous silvery-white metal

Physical state: Solid at room temperature

Half-life: From 1.37(17) milliseconds to 1.8(0.2)×1018 years

Electronegativity according to Pauling: 1.7

Density: 19.3 g.cm-3 at 20°C

Melting point: 3414°C, 6177°F, 3687 K

Boiling point: 5555°C, 10031°F, 5828 K

Van der Waals radius: 0.137 nm

Ionic radius: 0.068 nm (+4); 0.067 nm (+6)

Isotopes: 33

Most characteristic isotope: 182W, 184W, 186W

Electronic shell: [Xe] 4f14 5d4 6s2

The energy of the first ionization: 768.6 kJ.mol-1

The energy of the second ionization: N/A

Discovery date: In 1783 by Juan and Fausto Elhuyar

In the periodic table, tungsten is classified under the symbol W, atomic number 74, atomic mass of 183.85 g.mol-1, and electron configuration [Xe] 4f14 5d4 6s2, pure tungsten is an extremely hard, ductile, and dense silvery-white lustrous metal. It reaches its boiling point at 5555°C, 10031°F, 5828 K, while the melting point is achieved at 3414°C, 6177°F, 3687 K. 

This chemical element has the highest melting points and the highest tensile strength of all metals classified in the periodic table. As a member of the transition metals family of elements in the periodic table, tungsten has an electronegativity of 1.7 according to Pauling, whereas the atomic radius according to van der Waals is 0.137 nm. 

Tungsten is an exceptionally dense element, even denser than gold. It’s also one of the five major refractory metals, together with molybdenum, niobium, tantalum, and rhenium. When exposed to air, tungsten metal tarnishes and forms a protective oxide coating.                   

How Was Tungsten Discovered?

The two Spanish chemists and brothers Juan José and Fausto Elhuyar are credited as the first discoverers of element 74. They succeeded in isolating tungsten by reduction of acidified wolframite with charcoal in 1783.

Prior to their discovery, the Irish chemist and mineralogist Peter Woulfe (1727–1803) observed an unfamiliar substance during his analysis of the mineral wolframite. In 1781, the German-Swedish chemist Carl Wilhelm Scheele (1742-1786) successfully isolated tungstic oxide (WO3) by performing chemical analysis on the mineral scheelite (calcium tungstate). Sheele’s discovery later traced the root to the discovery of a new metal for Juan and Fausto Elhuyar. 

How Did Tungsten Get Its Name?

There are two names in use of element 74 – tungsten and wolfram. Both names have been around since its discovery. The name ‘tungsten’ originates from the Swedish words ‘tung sten’ that mean ‘heavy stone’, while the name ‘wolframite/wolfram’ is derived from the German phrase ‘wolf ram’, meaning ‘wolf dirt’. In the periodic table, element 74 has the Swedish name tungsten but is classified under the chemical symbol W (the first letter of its german name).

Origin of the Name ‘Wolfram”

During the middle ages, German miners of tin were often complaining about a mineral that was occurring alongside the tin ores. It was the wolframite mineral that was substituting part of the mined tin ore in the mining process, thus reducing the yield of tin. Due to the physical appearance of wolframite, the minders started referring to it as ‘a wolf that eats their tin ore’. 

Origin of the Name ‘Tungsten’

The mineral scheelite was discovered in 1750 in Sweden. The miners employed to excavate iron from this Swedish mine were intrigued by the hardness and density of this mineral, which is why they called it ‘a heavy stone’. 

Where Can You Find Tungsten?

Known since prehistoric times, element 47 has been created in the Universe by the explosion of massive stars and dispersed on our planet with a speed that amounts to 10% of the speed of light. The list of tungsten-rich minerals that occur in the Earth’s crust includes the following items:

 

• Anthoinite
• Billwiseite
• Ferberite
• Hübnerite
• Hydrokenoelsmoreite
• Johnsenite-(Ce)
• Khomyakovite
• Manganokhomyakovite
• Qusongite
• Raspite
• Russellite
• Scheelite
• Stolzite
• Tungsten
• Tungstite
• Wolframite
  

 

Tungsten is primarily obtained from the minerals scheelite [calcium tungstate (CaWO4)] and wolframite [an iron manganese tungstate (Fe,MnWO4)] by the same method used by the Elhuyar brothers from Spain. Namely, it’s isolated from the minerals by reducing tungsten oxide with hydrogen or carbon.

The richest deposits of tungsten ore are found in The Almonty Korea Tungsten deposit (Sangdong Mine), while Portugal, Vietnam, Russia, Canada, Bolivia, and China, are the largest producers of tungsten in the world.

Tungsten in Everyday Life

This transition metal is commonly used in metallurgy and technology:

• Tungsten was widely used in filaments in lamps and incandescent light bulbs. The wire filaments are made by sintering tungsten powder at high temperatures. Nowadays, it’s more often replaced with other materials, since this type of light gives off more heat than light. 
• Tungsten salts are used in fireproof fabrics, but also for sawing of theatrical costumes;
• Tungsten steel is used in the production of rocket engine nozzles for its excellent heat resistant properties;
• Element 74 is applied in the production of microchip technology and liquid crystals displays, vacuum tube filaments, heating elements,
• The high melting point makes tungsten an ideal material for aerospace and high-temperature applications, such as electrical, heating, as well as in the gas tungsten arc welding process, and other high-temperature applications;
• Tungsten is often used in both super-alloys and heavy metal alloys such as high-speed steel. Tungsten alloys are commonly used for manufacturing high-speed cutting tools, tips of drill bits, and mining machinery.

How Dangerous Is Tungsten?

All tungsten compounds are considered highly toxic substances. Upon skin contact, it may trigger redness and itchiness as the main signs of skin inflammation. When inhaled, dust particles of tungsten metal may irritate the lungs and mucous membranes. The metal dust of this chemical element also presents a fire and explosion hazard.

Most of the tungsten that enters our body is eliminated within a short time via the urinary tract. However, small accumulations can remain in the bones. Due to this, tungsten is considered to have a carcinogen potential. 

Environmental Effects of Tungsten

Due to its rare natural occurrence, there is no known danger associated with tungsten exposure of humans or the environment. 

Isotopes of Tungsten

There are 34 observed isotopes of this chemical element. Naturally occurring tungsten (74W) consists of four stable isotopes and one slightly radioactive isotope – 182W, 183W, 184W, 186W, and the radioisotope 180W. The tungsten-180 isotope is also the lightest living form of element 74, with a half-life of 1.8(0.2)×1018 years.

Nuclide [n 1]	Z	N	Isotopic mass (Da) [n 2][n 3]	Half-life [n 4][n 5]	Decay mode [n 6]	Daughter isotope [n 7][n 8]	Spin and parity [n 9][n 5]	Natural abundance (mole fraction)
	Excitation energy							Normal proportion	Range of variation
158W	74	84	157.97456(54)#	1.37(17) ms	α	154Hf	0+
159W	74	85	158.97292(43)#	8.2(7) ms	α (82%)	155Hf	7/2−#
					β+ (18%)	159Ta
160W	74	86	159.96848(22)	90(5) ms	α (87%)	156Hf	0+
					β+ (14%)	160Ta
161W	74	87	160.96736(21)#	409(16) ms	α (73%)	157Hf	7/2−#
					β+ (23%)	161Ta
162W	74	88	161.963497(19)	1.36(7) s	β+ (53%)	162Ta	0+
					α (47%)	158Hf
163W	74	89	162.96252(6)	2.8(2) s	β+ (59%)	163Ta	3/2−#
					α (41%)	159Hf
164W	74	90	163.958954(13)	6.3(2) s	β+ (97.4%)	164Ta	0+
					α (2.6%)	160Hf
165W	74	91	164.958280(27)	5.1(5) s	β+ (99.8%)	165Ta	3/2−#
					α (.2%)	161Hf
166W	74	92	165.955027(11)	19.2(6) s	β+ (99.96%)	166Ta	0+
					α (.035%)	162Hf
167W	74	93	166.954816(21)	19.9(5) s	β+ (>99.9%)	167Ta	3/2−#
					α (<.1%)	163Hf
168W	74	94	167.951808(17)	51(2) s	β+ (99.99%)	168Ta	0+
					α (.0319%)	164Hf
169W	74	95	168.951779(17)	76(6) s	β+	169Ta	(5/2−)
170W	74	96	169.949228(16)	2.42(4) min	β+(99%)	170Ta	0+
					α (1%)	166Hf
171W	74	97	170.94945(3)	2.38(4) min	β+	171Ta	(5/2−)
172W	74	98	171.94729(3)	6.6(9) min	β+	172Ta	0+
173W	74	99	172.94769(3)	7.6(2) min	β+	173Ta	5/2−
174W	74	100	173.94608(3)	33.2(21) min	β+	174Ta	0+
175W	74	101	174.94672(3)	35.2(6) min	β+	175Ta	(1/2−)
176W	74	102	175.94563(3)	2.5(1) h	EC	176Ta	0+
177W	74	103	176.94664(3)	132(2) min	β+	177Ta	1/2−
178W	74	104	177.945876(16)	21.6(3) d	EC	178Ta	0+
179W	74	105	178.947070(17)	37.05(16) min	β+	179Ta	(7/2)−
180W[n 10]	74	106	179.946704(4)	1.8(0.2)×1018 y	α	176Hf	0+	0.0012(1)
181W	74	107	180.948197(5)	121.2(2) d	EC	181Ta	9/2+
182W	74	108	181.9482042(9)	Observationally Stable[n 11]			0+	0.2650(16)
183W	74	109	182.9502230(9)	Observationally Stable[n 12]			1/2−	0.1431(4)
184W	74	110	183.9509312(9)	Observationally Stable[n 13]			0+	0.3064(2)
185W	74	111	184.9534193(10)	75.1(3) d	β−	185Re	3/2−
186W	74	112	185.9543641(19)	Observationally Stable[n 14]			0+	0.2843(19)
187W	74	113	186.9571605(19)	23.72(6) h	β−	187Re	3/2−
188W	74	114	187.958489(4)	69.78(5) d	β−	188Re	0+
189W	74	115	188.96191(21)	11.6(3) min	β−	189Re	(3/2−)
190W	74	116	189.96318(18)	30.0(15) min	β−	190Re	0+
191W	74	117	190.96660(21)#	20# s [>300 ns]			3/2−#
192W	74	118	191.96817(64)#	10# s [>300 ns]			0+

Source: Wikipedia

List of Tungsten Compounds 

Tungsten is a relatively stable chemical element. In chemical compounds, this transition metal typically adopts the oxidation state of +6, but it can also exhibit oxidation states from -2 to +6. 

The most common compounds of tungsten are listed below:

 

• Cemented carbide
• Copper–tungsten
• Elkonite
• Hexa(tert-butoxy)ditungsten(III)
• Sodium tungsten bronze
• Tungsten borides
• Tungsten carbide
• Tungsten dichloride dioxide
• Tungsten diselenide
• Tungsten disilicide
• Tungsten disulfide
• Tungsten ditelluride
• Tungsten hexachloride
• Tungsten hexafluoride
• Tungsten nitride
• Tungsten pentafluoride
• Tungsten pentoxide
• Tungsten trioxide
• Tungsten(II) chloride
• Tungsten(III) chloride
• Tungsten(III) oxide
• Tungsten(IV) chloride
• Tungsten(IV) fluoride
• Tungsten(IV) oxide
• Tungsten(V) bromide
• Tungsten(V) chloride
• Tungsten(VI) oxytetrabromide
• Tungsten(VI) oxytetrachloride
• Tungsten(VI) oxytetrafluoride
  

5 Interesting Facts and Explanations

1. Since the discovery of element 74, two names have been used for it: tungsten and wolfram. While ‘tungsten’ is a preferred name of this chemical in the United States and the UK, the name ‘wolfram’ is more common in European countries. 
2. Tungsten is the heaviest chemical element that has a biological role. Namely, it participates in the enzyme processes in some bacteria and archaea. 
3. Elements like tungsten that have a higher atomic number than iron cannot be created in the stars by a nuclear fusion.
4. The Bessemer process is the first industrial method that has enabled mass production of steel, including tungsten steel.   
5. While investigating the fluorescent ability of materials upon their exposure to x-rays, the great American inventor Tomas Alva Edison observed calcium tungstate as the most effective substance. The first tungsten filament lamps were made in 1904, by a Hungarian company called Tungsram.