22TiTitanium

Titanium is a chemical element with the symbol Ti and atomic number 22. Found in nature only as an oxide, it can be reduced to produce a lustrous transition metal with a silver color, low density, and high strength, resistant to corrosion in sea water, aqua regia, and chlorine.

Titanium was discovered in Cornwall, Great Britain, by William Gregor in 1791 and was named by Martin Heinrich Klaproth after the Titans of Greek mythology. The element occurs within a number of minerals, principally rutile and ilmenite, which are widely distributed in the Earth's crust and lithosphere; it is found in almost all living things, as well as bodies of water, rocks, and soils. The metal is extracted from its principal mineral ores by the Kroll and Hunter processes. The most common compound, titanium dioxide, is a popular photocatalyst and is used in the manufacture of white pigments. Other compounds include titanium tetrachloride (TiCl4), a component of smoke screens and catalysts; and titanium trichloride (TiCl3), which is used as a catalyst in the production of polypropylene. Titanium can be alloyed with iron, aluminium, vanadium, and molybdenum, among other elements, to produce strong, lightweight alloys for aerospace (jet engines, missiles, and spacecraft), military, industrial processes (chemicals and petrochemicals, desalination plants, pulp, and paper), automotive, agriculture (farming), medical prostheses, orthopedic implants, dental and endodontic instruments and files, dental implants, sporting goods, jewelry, mobile phones, and other applications. The two most useful properties of the metal are corrosion resistance and strength-to-density ratio, the highest of any metallic element. In its unalloyed condition, titanium is as strong as some steels, but less dense. There are two allotropic forms and five naturally occurring isotopes of this element, 46Ti through 50Ti, with 48Ti being the most abundant (73. 8%).

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Atomic properties

Standard atomic weight47.867 ±0.001
Atomic mass47.8671 u

Atomic radii

Radius (empirical)147 pm
Radius (calculated)176 pm
Covalent radius160 ±8 pm

Atomic shell

Electron configurationAr 3d2 4s2
Ionization energy(1st) 6.82812 eV
(2nd) 13.5755 eV
(3rd) 27.49171 eV
(4th) 43.26717 eV
(5th) 99.299 eV
Shell model
Electrons
k-shell:2
l-shell:8
m-shell:10
n-shell:2

Physical properties

Phasesolid
Density4.5 g·cm−3 (298.1 K)
Molar volume1.064·10-5 m3·mol−1
Speed of sound4,140 m·s−1 (293.1 K)

Temperatures

Melting point1,941 K
Boiling point3,560 K
Liquid range1,619 K
Transition temperature0.5 K

Enthalpies

Melting enthalpy18.7 kJ·mol-1
Enthalpy of vaporization425 kJ·mol-1
Binding energy471 kJ·mol-1

Heat and conductivity

Specific heat capacity523 J·kg−1·K−1
Thermal conductivity22 W·m-1·K-1
Expansion coefficient8.6·10-6 K-1
Work function4.33 eV

Hardnesses

Mohs hardness6
Brinell hardness716 NM·m-2
Vickers hardness970 NM·m-2

Elastic properties

Young’s modulus116 GPa
Shear modulus44 GPa
Bulk modulus110 GPa
Poisson’s ratio0.32

Electrical properties

Electrical conductivity2.5·106 S·m-1
Resistance4·10-7 Ωm

Magnetism

Magnetismparamagnetic
Magnetic susceptibility1.53·10-4 cm3·mol−1 (293 K)

Chemical properties

Basicityamphoteric
Oxidation state+2, +3, +4
Standard potential-0.86 V (TiO2+ + 2H+ + 4e- → Ti + H2O)

Electronegativity

Pauling scale1.54
Sanderson scale1.09
Allred-Rochow scale1.32
Ghosh-Gupta scale3.004 eV
Nagle scale1.23
Pearson absolute negativity3.45 eV

Other properties

Natural occurrenceprimordial
Crystal structureHexagonal close-packed
Goldschmidt Classificationlithophile
Superconductorwith transition tempperature (solid body, normal pressure)
Price/kg11.4 ±0.3 USD

Natural abundances

satellite_alt
Universe
3,000 ppb ≈ 3.01·1013 M☉
sunny
Sun
4,000 ppb ≈ 7.95·1012 Mt
destruction
Meteorite
550,000 ppb ≈ 550 g
public
Earth’s crust
6.6·106 ppb ≈ 1.82·108 Mt
water_drop
Oceans
1 ppb ≈ 1.37 Gt
waves
Flowing water
3 ppb ≈ 48 kt
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