Titanium – facts and properties
- Symbol
- Ti
- Atomic number
- 22
- Atomic mass
- 47.867 u
- Period
- 4
- Group
- 4
- Category
- transition metal
- Electron configuration
- [Ar] 3d² 4s²
- Electronegativity
- 1.54
- Atomic radius
- 176 pm
- Valence electrons
- 4
- State at standard conditions
- solid
- Melting point
- 1668 °C
- Boiling point
- 3287 °C
- Density
- 4.5 g/cm³
- Discovered
- 1791
Titanium is a lustrous, silvery transition metal with atomic number 22. It combines two qualities that rarely go together: it is nearly as strong as steel but only a little more than half as heavy. It hardly corrodes and the human body tolerates it well. You meet titanium dioxide even more often than the metal, because it is the most important white pigment, found in wall paint, paper and sunscreen.
Position in the periodic table
Occurrence and extraction
Titanium is among the ten most abundant elements in the Earth's crust. It never occurs as a native metal but in minerals such as ilmenite, an iron titanium oxide, and rutile, which is titanium dioxide. These minerals often form heavy, dark sands along coastlines, for example in Australia, South Africa and Mozambique.
In 1791, William Gregor, an English clergyman and amateur mineralogist, found an unknown metal oxide in sand from a valley in Cornwall. A few years later the German chemist Martin Heinrich Klaproth came across the same element in rutile and named it after the Titans of Greek mythology. Making the pure metal was impossible for a long time, because hot titanium reacts with oxygen, nitrogen and carbon.
Today nearly all titanium is made by the Kroll process, developed around 1940. Titanium dioxide is first reacted with coke and chlorine to give titanium tetrachloride, a liquid that can be purified by distillation. Under an inert gas, the tetrachloride is then reduced with molten magnesium. The product is a porous titanium sponge, which is remelted in a vacuum. The process is slow and uses a lot of energy, which is why titanium costs far more than steel or aluminium.
Properties and reactions
Titanium is in period 4 and group 4, and its electron configuration is [Ar] 3d² 4s². With four outer electrons, its most common oxidation state is plus four, as in titanium dioxide, TiO₂. Its electronegativity is 1.54.
At a density of 4.5 g/cm³, titanium is much lighter than iron. It melts only at 1668 °C and boils at 3287 °C. Titanium alloys are very strong and keep their strength up to several hundred degrees Celsius. The metal is not ferromagnetic and conducts heat and electricity relatively poorly.
Chemically, titanium is actually a reactive metal. It resists corrosion thanks to an extremely thin, dense film of titanium dioxide that forms instantly in air and shields the metal underneath. If the film is scratched, it grows back by itself. That is why titanium withstands even seawater and aqueous chlorine solutions. At high temperatures, however, the film offers no protection: fine titanium powder is flammable, and red-hot titanium will even burn in pure nitrogen.
Uses in everyday life and technology
Most titanium ore is never turned into metal at all. Instead it becomes titanium dioxide, a pigment that is non-toxic, lightfast and covers surfaces extremely well. It makes wall paints, coatings, plastics, paper and toothpaste white. In sunscreens, fine titanium dioxide particles scatter and absorb ultraviolet radiation. As the food additive E171 it has been banned in the EU since 2022, after the European Food Safety Authority concluded in 2021 that concerns about possible damage to genetic material by the particles, especially the nano fraction, could not be ruled out.
Titanium metal and its alloys are chosen wherever low weight, high strength and corrosion resistance matter: in aircraft structures and jet engines, in rockets, in chemical plants and in seawater desalination plants. The most widely used alloy contains small amounts of aluminium and vanadium.
In medicine, titanium is the standard material for dental implants, artificial hip joints and bone screws. Bone grows directly onto its oxide surface, and rejection is rare. Spectacle frames, watch cases, bicycle frames and jewellery are also made from titanium.
Molecules containing this element
- Strontium titanate SrTiO3
- Barium titanate BaTiO3
- Titanium(IV) butoxide Ti(OC4H9)4
Quick question
What is the atomic number of titanium (Ti)?
FAQ
Is titanium magnetic?
No, titanium is not ferromagnetic, so a magnet will not pick it up the way it picks up iron, nickel or cobalt. This is one reason why people with titanium implants can usually have an MRI scan.
Why is titanium so expensive?
Titanium ore is not scarce, but extracting the metal is difficult. Because hot titanium reacts with air, producers have to go via titanium tetrachloride and reduce it with magnesium. The Kroll process runs in batches, needs a lot of energy and yields a sponge that still has to be remelted.
Is titanium toxic?
Titanium metal is very well tolerated, which is why it is the leading metal for implants. Coarse titanium dioxide in paints and cosmetics is also regarded as safe. In 2021 the European Food Safety Authority could no longer consider titanium dioxide safe as a food additive, and the European Commission then banned E171 in food in 2022.