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Zirconium

What is Zirconium

Zirconium (pronunciation: zer-KO-nee-em) is a hard, silvery-gray element that belongs to the group of transition metals and is represented by the chemical symbol Zr [1, 2, 3]. It is a malleable and ductile metallic element that can readily react with other elements to form stable compounds [2].

Zirconium

Isotopes of Zirconium

Zirconium has four stable, naturally occurring isotopes, including 90Zr, 91Zr, 92Zr, and 94Zr with a natural abundance of 51.45%, 11.22%, 17.15%, and 17.38% respectively [4]. There are roughly 29 radioisotopes out of which the two most stable are 96Zr and 93Zr with half-lives of about 2.0 X 1019 years and 1.53 million years respectively [4].

Where is Zirconium Found

Zirconium is naturally found in several mineral species, mainly in zircon (zirconium silicate or ZrSiO4) and baddeleyite (zirconium dioxide or zirconia or ZrO2) [1, 2]. The metal is commercially isolated from zircon by first converting it to zirconium chloride and then through magnesium reduction of chloride [1]. The top 3 zirconium reserve holding countries are Australia, South Africa, and Ukraine while the top 3 producers are Australia, South Africa, and China [1].

History

Origin of its Name: The element is named from the Arabic word ‘zargun’, which means ‘gold-colored’ [1].

Who discovered it: Zirconium was discovered by the German chemist Martin Heinrich Klaproth [1].

When and How was it Discovered

In the ancient times, gemstones containing zirconium were known as zircon [1]. Martin Klaproth, in 1789, investigated zircon and separated the new element in the form of baddeleyite or zirconia, the oxide of zirconium [1].

Klaproth could not successfully isolate the pure metal while Humphry Davy was also unsuccessful in splitting zirconia through electrolysis in 1808 [1, 5].  In 1824, the Swedish chemist Jöns Jacob Berzelius isolated zirconium in black, powdery form by heating potassium hexafluorozirconate with potassium [1].

However, the entirely pure form was not produced until 1925 when the Dutch chemists Jan Hendrik de Boer and Anton Eduard van Arkel decomposed zirconium tetraiodide (ZrI4) [1]. Today, the metal is manufactured in bulk through reduction of ZrI4 by magnesium [1].

Zirconum Symbol

Zirconium Identification

Atomic number 40 [1]
CAS number 7440-67-7 [1]
Position in the periodic table Group Period Block
  4 [1] 5 [1] d [1]

Properties and Characteristics of Zirconium

General Properties

Relative atomic mass 91.224 [1]
Atomic mass 91.224 amu [1]
Molar mass 91.2240 g/mol [6]

Physical Properties

Color Silvery, grayish-white [1, 5]
Melting point/freezing point 1854 °C, 3369 °F [1]
Boiling point 4406 °C, 7963 °F [1]
Density 6.52 g cm-3 [1]
State of matter at room temperature (solid/liquid/gas) Solid [1, 5]
Hardness
– Brinell 650 MPa [7]
– Mohs 5 [7]
– Vickers 904 MPa [7]
Electrical Conductivity 2.4 X 106 S/m [7]
Charge +4 [8]
Thermal (heat) conductivity 23 W/(m K) [7]
Specific heat 278 J kg-1 K-1 [1]
Bulk modulus Unknown [1]
Shear modulus Unknown [1]
Young’s modulus Unknown [1]
Vapor pressure
– Temperature (K) 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400
– Pressure (Pa) 1.05 X 10-10 6.17 X 10-8 8.68 X 10-6 0.45 X 10-3 0.011 0.155

Chemical Properties

Oxidation states 4 [1]
Isotopes Isotope Mass Abundance (%) Half-life Mode of decay
  90Zr 89.905 51.45
  91Zr 90.906 11.22
  92Zr 91.905 17.15
  94Zr 93.906 17.38 > 1017 y β-β-
  96Zr 95.908 2.8 2.3 X 1019 y β-β-
    > 1.7 X 1018 y β-

Zirconium Lewis Dot Structure

Atomic Data of Zirconium (Element 40)

Valence electrons 4 [9]
Quantum numbers
– n 4 [10]
– ℓ 2 [10]
– m -1 [10]
– ms +1/2 [10]
Electron configuration (noble gas configuration) [Kr] 4d25s2 [1]
Atomic structure
– Number of electrons 40 [5]
– Number of neutrons 51 [5]
– Number of protons 40 [5]
Radius of Atom
– Atomic radius 2.23 Å [1]
– Covalent radius 1.64 Å [1]
Electronegativity (Pauling-scale) 1.33 [1]
Electron affinity 41.103 [1]
Ionization energy (kJ mol-1) 1st 2nd 3rd 4th 5th 6th 7th 8th
  640.074 1264 2218.2 3313.31 7752.404

Zirconium Electron Configuration (Bohr Model)

What is it Used for

  • Since it is not good at absorbing neutrons, it is used to provide the outer covering for the fuel rods in nuclear reactors [1, 5]. The reactors in nuclear power stations can have over 100,000 meters of zirconium tubing [1].
  • Being superconductive at low temperatures, the alloy of zirconium and niobium is used for making superconducting magnets [1, 5].
  • Zirconium(IV) oxide is used to make ultra-strong ceramics, which can be used for manufacturing crucibles, furnace linings, abrasives, and foundry bricks because of its heat-resistant properties [1]. It is used in antiperspirants, cosmetics, microwave filters, and food packaging industries [1].
  • The natural gemstone zircon is available in various colors, out of which the most desirable is the golden one that is used for making jewelry [1]. The colorless, cubic zirconia is used as a synthetic gemstone, and when cut, it resembles a diamond [1].
  • Since zirconium is exceptionally resistant to corrosion, it is useful in corrosive environments, and its alloys are found in heat exchangers, pipes, and fittings [5].
  • Zirconium silicate mixed with praseodymium or vanadium produces yellow and blue pigments for painting pottery [1].
  • Porcelain veneered zirconium crowns, implant dentures, and bridges are used for replacing lost teeth [11].
  • Since zirconium powder can naturally ignite in air, it may be used in explosive devices [2].

Cubic Zirconium

Zirconium Toxicity

Zirconium is known to have low toxicity, and if exposed, people may experience irritation of skin and eyes [12]. If inhaled, it can cause the formation of tumors in the lungs [12]. It is not known to play any biological role [1].

Interesting Facts

  • It is reported that over 1.5 million tons of zircon are mined annually, mainly in South Africa and Australia [1].
  • Zirconium is graphically represented as a scarab beetle because zircon gemstones were used in jewelry by the ancient Egyptians who related scarab beetles with creation, transformation, and regeneration [1].
  • The element is so strong that it can be used for producing knives and scissors [1].

Black Zirconium

Zirconium Cost

The price of pure zirconium is about $1.57 per gram, and in bulk, it costs roughly $0.16 per gram [5].

References

  1. http://www.rsc.org/periodic-table/element/40/zirconium
  2. https://www.livescience.com/34610-zirconium.html
  3. https://education.jlab.org/itselemental/ele040.html
  4. https://education.jlab.org/itselemental/iso040.html
  5. https://www.chemicool.com/elements/zirconium.html
  6. https://www.webqc.org/molecular-weight-of-zirconium.html
  7. http://periodictable.com/Elements/040/data.html
  8. https://www.chemthes.com/entity_datapage.php?id=857
  9. https://zirconium2015.weebly.com/about-zirconium.html
  10. http://chemistry-reference.com/q_elements.asp?Symbol=Zr
  11. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3399177/
  12. http://metalpedia.asianmetal.com/metal/zirconium/health.shtml

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