Titanium - Ti

Titanium (Ti) is a strong, relatively light transition metal with excellent corrosion resistance in many environments. Its metal, alloys and compounds have different properties and uses: titanium metal is used in demanding equipment, while titanium dioxide (TiO₂) is widely used as a white pigment.

Chemical properties · Applications · Titanium and water treatment · Health effects · Environmental effects

Selected properties of titanium metal
Symbol / atomic number	Ti / 22
Standard atomic weight	47.867(1)
Group / period / block	4 / 4 / d
Electron configuration	[Ar] 3d² 4s²
Electronegativity (Pauling)	1.54
Density	4.506 g cm⁻³ at room temperature
Melting point	1670 °C
Boiling point	3287 °C
Covalent radius	0.148 nm
Non-bonded radius	0.211 nm
Common oxidation states	+4 and +3
Naturally occurring isotopes	⁴⁶Ti, ⁴⁷Ti, ⁴⁸Ti, ⁴⁹Ti and ⁵⁰Ti
First ionisation energy	658.8 kJ mol⁻¹
Discovery	William Gregor, 1791

Property values follow the Royal Society of Chemistry; the standard atomic weight follows CIAAW. Atomic weight is dimensionless; the corresponding molar mass is approximately 47.867 g mol⁻¹. The number in parentheses indicates uncertainty in the final digit. Ionic radii depend on oxidation state and coordination and are therefore not given as a single value.

Two pieces of titanium metal — Titanium metal.

Titanium: properties and occurrence

Titanium has a high strength relative to its weight. A thin, adherent oxide film forms on its surface in air and helps protect the underlying metal from corrosion. This passive film explains why a chemically reactive element can perform well in many corrosive service conditions. Resistance is not universal: titanium grade, temperature, water chemistry and equipment design all matter.

Titanium occurs in minerals rather than as free metal. Important mineral sources include ilmenite (FeTiO₃) and rutile (TiO₂). Anatase and brookite are other crystalline forms of titanium dioxide. Mining, pigment manufacture and titanium-metal production are distinct stages and should not be confused.

William Gregor identified the element in a Cornish mineral in 1791. Martin Heinrich Klaproth independently identified it and gave it the name titanium in 1795.

Applications of titanium and its compounds

Metal and alloys: aerospace components, chemical-processing equipment and marine applications benefit from titanium's strength, relatively low density and corrosion resistance.
Medical devices: suitable titanium grades and alloys are used in dental and orthopaedic implants. Device performance depends on the material, surface, design and clinical application.
Titanium dioxide: its optical properties make it an important white pigment in paints, plastics and paper. Pigment-grade material and nanoscale photocatalysts are not interchangeable products.
Functional materials: titanium compounds are also used in ceramics and other specialised materials.

Titanium and water treatment

For reactions, occurrence and water-quality information, see Titanium in water (Ti + H₂O).

Corrosion-resistant equipment

Titanium is used in seawater condensers and heat exchangers, including equipment for desalination. Here it serves as a construction material; it does not itself remove salt from water. Material selection must consider the full operating and cleaning conditions rather than relying on a general corrosion-resistance claim.

Coated titanium electrodes

Titanium can provide the supporting substrate for mixed-metal-oxide-coated anodes used to protect steel structures in water. The active coating gives the electrode its intended electrochemical performance. Bare titanium and a purpose-designed coated anode should not be treated as equivalent.

Titanium dioxide photocatalysis

Under suitable illumination, TiO₂ can act as a photocatalyst and promote oxidation of organic contaminants. Government research has investigated this approach for contaminated-water treatment. Performance depends on the light source, catalyst, contaminant and water matrix; a successful demonstration for one compound does not establish removal of every contaminant. Treatment claims require validation for the proposed application.

When investigating titanium in a water sample, distinguish dissolved titanium from titanium-bearing particles and TiO₂. The analytical method and sample preparation affect what is measured. Treatment selection should follow characterisation and testing rather than an assumption that every form behaves alike.

Health effects of titanium

Titanium has no established essential biological role in humans. Bulk metal, soluble compounds, pigment particles and nanoscale TiO₂ can present different exposure conditions. The use of titanium in medical devices does not establish that every titanium-containing material is harmless by every route of exposure.

IARC classifies titanium dioxide as possibly carcinogenic to humans (Group 2B), based on sufficient evidence in experimental animals and inadequate evidence in humans in its evaluation. This classification concerns TiO₂; it is not a classification of all titanium materials. A hazard classification alone does not quantify the risk from a particular product or exposure.

In workplaces, inhalation of airborne TiO₂ dust deserves attention. NIOSH distinguishes fine from ultrafine, including nanoscale, particles in its exposure assessment. Use appropriate dust controls and the safety data sheet for the actual material. Finely divided titanium metal can also pose serious fire and dust hazards even though a solid component behaves very differently.

Environmental effects of titanium

Titanium-bearing minerals occur naturally in soils and sediments. Environmental behaviour depends on chemical form, particle characteristics and exposure conditions. Natural occurrence is not evidence that every release is harmless, and the effects of nanoscale TiO₂ should not be inferred directly from those of bulk metal or mineral grains.

For industrial wastewater and treatment residuals, identify the titanium-containing material and any associated contaminants before selecting treatment, reuse or disposal arrangements. Environmental assessments need to consider the specific material and receiving environment.

Titanium page last reviewed: 24 October 2026 by Lenntech.