|
General |
Name, Symbol, Number | Titanium, Ti, 22 |
Chemical series | Transition metals |
Group, Period, Block | 4[?], 4 , d |
Density, Hardness | 4507 kg/m3, 6 |
Appearance | Silvery metallic |
Atomic Properties |
Atomic weight | 47.867 amu |
Atomic radius (calc.) | 140 (176) pm |
Covalent radius | 136 pm |
van der Waals radius | no data |
Electron configuration | [Ar]3d2 4s2 |
e- 's per energy level | 2, 8, 10, 2 |
Oxidation state (Oxide) | 4 (amphoteric) |
Crystal structure | Hexagonal |
Physical Properties |
State of matter | Solid (__) |
Melting point | 1941 K (3034 °F) |
Boiling point | 3560 K (5949 °F) |
Molar volume | 10.64 ×10-3 m3/mol |
Heat of vaporization | 421 kJ/mol |
Heat of fusion | 15.45 kJ/mol |
Vapor pressure | 0.49 Pa at 1933 K |
Velocity of sound | 4140 m/s at 293.15 K |
Miscellaneous |
Electronegativity | 1.54 (Pauling scale) |
Specific heat capacity | 520 J/(kg*K) |
Electrical conductivity | 2.34 106/m ohm |
Thermal conductivity | 21.9 W/(m*K) |
1st ionization potential | 658.8 kJ/mol |
2nd ionization potential | 1309.8 kJ/mol |
3rd ionization potential | 2652.5 kJ/mol |
4th ionization potential | 4174.6 kJ/mol |
5th ionization potential | 9581 kJ/mol |
6th ionization potential | 11533 kJ/mol |
7th ionization potential | 13590 kJ/mol |
8th ionization potential | 16440 kJ/mol |
9th ionization potential | 18530 kJ/mol |
10th ionization potential | 20833 kJ/mol |
Most Stable Isotopes |
|
SI units & STP are used except where noted. |
Titanium is a
chemical element in the
periodic table that has the symbol Ti and
atomic number 22. A light, strong, white-metallic, lustrous,
corrosion-resistant
transition metal, titanium is used in strong light-weight
alloys and in white pigments. This element occurs in numerous minerals with the main sources being
rutile and
ilmenite.
Titanium is a
metallic element which is well known for its excellent
corrosion resistance (almost as resistant as
platinum) and for its high strength-to-weight ratio. It is light, strong, easily fabricated metal with low
density that, when pure, is lustrous, and metallic-white. The relatively high
melting point of this element makes it useful as a
refractory metal[?]. Titanium is as strong as
steel, but 45% lighter and 60% heavier than
aluminium, but twice as strong.
This metal forms a passive oxide coating when exposed to air but when it is in an oxygen-free environment it is ductile. The metal, which burns when heated in air, is also the only element that can burn in pure nitrogen gas. Titanium is resistant to dilute sulfuric and hydrochloric acid, along with chlorine gas, chloride solutions, and most organic acids .
Experiments have shown that natural titanium becomes very radioactive after it is bombardment with deuterons emitting mainly positrons and hard gamma rays. The metal is dimorphic with the hexagonal alpha form changing into the cubic beta form very slowly at around 880° C. When it is red hot the metal combines with oxygen and when it reaches 550°C it combines with chlorine.
Approximately 95% of titanium is consumed in the form of
titanium dioxide (Ti
O2), a white permanent
pigment with good covering power in
paints,
paper, and
plastics. Paints made with titanium dioxide are excellent reflectors of
infrared radiation and are therefore used extensively by
astronomers.
Because of its strength, light weight and ability to withstand extreme temperatures, titanium alloys are principally used in aircraft and missiles, although applications in consumer products such as golf clubs[?], mountain bikes, and laptop computers[?] are becoming more common. Titanium is often alloyed with aluminum, iron, manganese, molybdenum and with other metals. Other uses;
- Due to excellent resistance to sea water, it is used to make propeller shafts and rigging.
- It is used to produce relatively soft artificial gemstones.
- Titanium tetrachloride[?] is used to iridize glass and because it fumes strongly in air it is also used to make smoke screens[?].
- Because it is considered to be physiologically inert, the metal is used in joint replacement implants such as hip ball and sockets.
- Because of both its inertness and its ability to be attractively colored, titanium is a popular metal for use in Body piercing.
A potential use of titanium is in desalination plants.
Titanium (
Latin Titans, the first sons of
Gaia) was
discovered in
England by Reverend
William Gregor[?] in
1791 who recognized the presence of a new element in
ilmenite. The element was rediscovered several years later by
German chemist
Heinrich Klaproth[?] in
rutile ore. In
1795 Klaproth named the new element after the
Titans of
Greek mythology.
Pure metallic titanium (99.9%) was first prepared in 1910 by Matthew A. Hunter[?] by heating TiCl4 with sodium in a steel bomb at 700-800°C.
Titanium metal wasn't used outside the laboratory until 1946 when William Justin Kroll[?] proved that titanium could be commercially produced by reducing titanium tetrachloride[?] with magnesium (which is the method still used today).
Titanium metal is not found unbound to other elements in nature but the element is the ninth most abundant element in the
earth's crust and is present in most
igneous rocks and in sediments derived from them. Titanium occurs primarily in the
minerals anatase,
brookite,
ilmenite,
leucoxene,
perovskite,
rutile, and
sphene and is found in
titanates and in many
iron ores. Of these minerals, only ilmenite, leucoxene, and rutile have significant economic importance. Significant titanium ore deposits are in
Australia,
Scandinavia,
North America and
Malaysia.
This metal is found in meteorites and has been detected in the sun and in M-type stars. Rocks brought back from the moon during the Apollo 17 mission are composed of 12.1% TiO2. Titanium is also found in coal ash, plants, and even the human body.
Titanium metal is produced commercially by reducing Ti
Cl4 with
magnesium, a process developed in
1946 by
William Justin Kroll[?]. This is a complex and expensive batch process, but a newer process called the "FFC-Cambridge" method may displace this older process. This method uses the feedstock titanium dioxide powder (which is a refined form of
rutile) to make the end product which is a continuous stream of molten titanium suitable for immediate use in the manufacture of commercial
alloys.
It is hoped that the FFC-Cambridge method will render titanium a less rare and expensive material for the aerospace industry and the luxury goods market, and will be seen in many products currently manufactured using aluminum and specialist grades of steel.
Although titanium metal is relatively uncommon, due to the cost of extraction,
titanium dioxide is cheap, readily available in bulk, and very widely used as a white
pigment in
paint,
plastic and construction
cement. TiO
2 powder is chemically inert, resists fading in sunlight, and is very opaque: this allows it to impart a pure and brilliant white color to the brown or gray chemicals that form the majority of household plastics. Pure titanium dioxide has a very high
index of refraction and an
optical dispersion higher than
diamond.
Star sapphires[?] and
rubies get their asterism from the titanium dioxide present in them.
Naturally occurring titanium is composed of 5 stable
isotopes; Ti-46, Ti-47, Ti-48, Ti-49 and Ti-50 with Ti-48 being the most abundant (73.8%
natural abundance). 11
radioisotopes have been characterized with the most stable being Ti-44 with a
half-life of 63 years, Ti-45 with a half-life of 184.8 minutes, Ti-51 with a half-life of 5.76 minutes, and Ti-52 with a half-life of 1.7 minutes. All of the remaining
radioactive isotopes have half-lifes that are less than 33 seconds and the majority of these have half lifes that are less than half a second.
The isotopes of titanium range in atomic weight from 39.99 amu (Ti-40) to 57.966 amu (Ti-58). The primary decay mode before the most abundant stable isotope, Ti-48, is electron capture and the primary mode after is beta emission. The primary decay products before Ti-48 are element 21 (scandium) isotopes and the primary products after are element 23 (vanadium) isotopes.
When in a powered form, titanium metal poses a significant fire hazard but
salts of titanium are often considered to be relatively harmless. Chlorine compounds such as TiCl
3 and TiCl
4 should be considered to be
corrosive, however. Titanium also has a tendency to
bio-accumulate in tissues that contain
silica but it does not play any known biological role in
humans.