The Element Titanium

The song “Titanium” by David Guetta ft. Sia, has the lyrics “You shoot me down, but I won’t fall; I am titanium”. Elemental titanium is one of the strongest metals- it is as strong as steel, but comparably, less dense and much more lightweight. Additionally, it is very resistant to extreme temperatures. This makes titanium element an awesome alloying agent for aircraft and spacecraft. 

This element is certainly as strong as the song implies.

Cool Facts About Titanium

1. Titanium’s name comes from the Titans of Greek mythology. 
2. Originally, titanium’s name was gregorite.
3. In nature, this element is almost always found in igneous rock and its sediments. Miners seek the minerals rutile and ilmenite.
4. On earth, rocks contain about 1% titanium. However, on the moon, there are clusters of titanium-rich rock that contain about 10% titanium. 
5. As learned, at higher temperatures, titanium is reactive with oxygen. During the production of titanium alloys, titanium’s oxide scale is removed to prevent the metal from turning brittle. 
6. Titanium is the ninth most abundant element on Earth; The Earth’s crust contains about 0.44% of it. Plants, animals, natural waters, and stars contain the element as well.

Titanium on the Periodic Table

Titanium is a transition metal with symbol Ti and atomic number 22. It lies in group 4, to the right of scandium, the left of vanadium, and above zirconium. Its chemistry and properties are somewhat similar to zirconium. It has an electronegativity of 1.54, and the titanium atom has an electron configuration of [Ar]3d²4s² or 1s²2s²2p⁶3s²3p⁶3d²4s²

Where is Titanium Found?

Titanium is the ninth most abundant element on Earth. It can be found in igneous rocks and the sediments derived from them. It occurs in the minerals rutile. ilmenite, and titanite and is present in many iron ores. Titanium is very widespread, and the largest producers of titanium sponge are China, Russia, the USA, and Japan.

Titanium’s high strength-to-weight ratio and resistance to corrosion make it a very valuable element. As said, titanium is as strong as steel, while weighing considerably less, and can withstand extreme temperature changes. Its resistance to corrosion is due to its ability to form a passive oxide surface film, which prevents electron transfer to its surroundings. 

In its pure form, it is a lustrous, shiny metal that is tough and ductile. It possesses low electrical and thermal conductivity and is paramagnetic.

Is Titanium Dangerous? 

As said, food products commonly contain TiO₂. While the FDA states that the pigment can be used to color foods, it strictly regulates how much can be added, as there is a limit of 1%. 

Inhaling titanium powder can affect the human’s lungs and cause pleural disease. It is carcinogenic and may cause cancer. 

In the environment, titanium is relatively safe. However, it still has its dangers. Titanium powder is flammable. When heated in air and exposed to oxygen, poses an explosion hazard. If it reacts with water at high temperatures, it releases hydrogen and can cause an explosion. 

Finding Titanium’s Weakness: Is it too good to be true?

Titanium seems pretty indestructible and almost immune to all things, as it is very adaptable to stress due to its elasticity. However, this is false. The metal is highly reactive with oxygen, and when the two elements mix, becomes very fragile and brittle. This makes it brittle and more susceptible to cracking. Oxygen is titanium’s biggest enemy.

Titanium’s Applications in Today’s World

The most common form of titanium utilization is via titanium dioxide (TiO₂) pigment. This is a non-toxic powder that is very opaque and white in color. Varnish, paper, glaze, and even food can all contain this pigment. Why is it so popular? TiO₂ has the +4 oxidation state- the most stable oxidation state- and is resistant to UV rays and discoloration, making it commonly found in paint, plastic, and sunscreen. Food products, such as marshmallows, chewing gum, and cake frosting, usually have TiO₂ to give an aesthetically pleasing white color. Additionally, the non-toxic powder gets added to materials like graphite for its strengthening properties. High-quality golf clubs are usually coated with the pigment.

Alloys of titanium contain other metals like aluminum and steel. These alloys are highly resistant and can survive corrosion, cracking, and extreme temperatures. Its high strength explains why this metal is so commonly used for making aircraft, spacecraft, naval ships, and landing gear. Additionally, this strong metal can withstand corrosion from saltwater. Therefore, ships, saltwater aquariums, fishing lines, and even some submarines, use titanium alloys. They are also utilized to make dental implants, as they do not break down when in contact with body fluids. Additionally, titanium alloys are used in prosthetic devices, because it is non-reactive to the body’s tissue and bone. Lastly, titanium is osteoconductive, meaning it promotes bone growth on the implant itself allowing for seamless integration into the skeletal structure.

In addition to being an extremely strong metal, titanium can also be color anodized in a variety of colors. Anodization is the directed oxidation of a metal’s surface; this is typically done using electrolysis. Anodization gives the metal a more resilient coating that is harder than the underlying base metal which makes this process very popular in the aerospace industry. Unlike aluminum anodization, however, colored titanium anodization does not require the use of a dye. Various colors can be produced by changing the voltage used for the electrolysis process. Each voltage results in the formation of a different thickness of oxide layer which yields a different color.

History of Titanium

How was titanium discovered, and who discovered it?

The history of titanium is quite unique. Two different chemists discovered titanium at two separate times- once in 1791 and once in 1795. British chemist, Reverend William Gregor discovered elemental titanium first. Then, a German chemist named Martin Heinrich Klaproth newly discovered the element again. How is this possible? Gregor was a mineralogist and was studying black sand in the Manaccan valley. He took a sample of the sand and was able to identify an oxide of iron and an unknown metal, that he named “menachanite”. This oxide was identified as ilmenite, one of titanium’s ores. Although he reported his findings to the Royal Geological Society of Cornwall, his contributions were forgotten about. A few years later, Klaproth rediscovered titanium while studying Schörl, a type of red ore and form of rutile (TiO₂). The scientist named the rutile “titanium”.

Titanium Reactions

Hydrochloric acid does not react with titanium unless it is hot, at which point it slowly dissolves titanium, resulting in the deep purple-colored titanium (III) chloride. This is the opposite of bismuth, where hydrochloric acid has no effect. Over time this compound will slowly oxidize to colorless titanium (IV). Titanium metal has a passivation layer of titanium oxide on at all times, similar to aluminum, which is why it can resist strong acids.

When titanium reacts with hot nitric acid, it turns insoluble. When dissolving the metal, the solvent of choice is hydrofluoric acid because it can both dissolve the metal and hold it in solution. 

Titanium behaves differently when exposed to different temperatures. At room temperature, the metal is brittle, while at high temperatures, it is more ductile and malleable. At elevated temperatures, titanium can react with oxygen to create titanium dioxide.

Experiments with Titanium

Titanium will slowly react with hot hydrochloric acid to produce the beautifully purple TiCl₃. Adding sodium fluoride will produce a green titanium (III) fluoro-complex, adding thiocyanate ion will produce an even more deeply purple colored thiocyanate complex. Adding sodium hydroxide will precipitate a beautiful blue colored titanium (III) hydroxide. Last, but not least, adding 30% hydrogen peroxide to aqueous TiCl₃ will produce a red colored titanium (IV) peroxy compound, Ti(O₂)(OH)⁺

Titanium Compounds

Oxides

Titanium oxide compounds form when titanium reacts with oxygen at high temperatures. The most important oxide is titanium dioxide, TiO₂, because it is low-cost, non-toxic, and chemically inert, making its applications widespread. In addition, it is the only naturally occurring titanium oxide. TiO₂ comes as a fine, white powder, which makes white pigment. Ever wonder how coffee creamer is so white? It contains TiO₂ pigment. Additionally, it forms different shapes with differing properties; TiO₂ exists in three forms: anatase, brookite, and rutile.

The anatase and brookite polymorphs are metastable, meaning that they are stable under only specific conditions. Otherwise, they may undergo spontaneous transformation; When heated, anatase and brookite irreversibly convert to the more stable rutile form. Anatase is a brown-black mineral that is transparent when light-colored and opaque when deeply colored. Brookite is a deep-red crystal that considered to be quite rare. Unfortunately, its foul smell makes it stand out from the rest. Rutile ores are the most abundant natural form of TiO₂. They are widespread in the Earth’s crust and are contain 98% TiO₂. Aside from producing titanium metal, they play a large role in the production of pigment and refractory ceramics. 

Titanium dioxide is very inert, resisting most acids even when heated, except for hydrofluoric acid.

Halides

Titanium halide compounds are the products of titanium combining with halogens. There are different types of halide compounds, including chlorides, iodides, and fluorides.

Chlorides

Titanium tetrachloride, TiCl₄, form when titanium reacts with dry chlorine at an elevated temperature. TiCl₄ is a smelly, heavy, colorless liquid with covalent bonds. Additionally, it is not present in nature and comes from processing other titanium-containing minerals. This may be a good thing, as it is the most toxic titanium compound. TiCl₄ is a corrosive, unstable compound that undergoes different reactions upon contact with other substances. When exposed to air, it fumes; when it comes in contact with water, it forms hydrochloric acid; when it reacts with alcohol, it forms an alkoxide. Despite its dangers, TiCl₄ is an important compound, as it is the intermediate product when commercially producing titanium. Furthermore, alkoxides are extremely vital to the industrial field. When alkoxides react with water, they convert to solid titanium dioxide, which, as discussed, has many vital properties.

Titanium trichloride, TiCl₃, is a lower and slightly more unstable chloride. The titanium atom of TiCl₃ consists of a d electron, and when this electron gets excited, it creates a distinguishable violet color. However, the Laporte selection rule prevents this beautiful color from being very opaque. The Laporte selection rule forbids transitions between two states with the same symmetry. Additionally, TiCl₃ is both a reducing agent and a catalyst for the production of propylene, which makes polypropylene. This chemical is found in many household items, such as ketchup bottles, potato chip bags, straws, and even carpet fibers. 

Titanium dichloride, TiCl₂, is highly reactive, and when exposed to air, catches on fire. Like TiCl₃, it is a reducing agent and forms stable chlorides. 

Titanium readily forms fluoride complexes in both the +3 and +4 oxidation states.

Iodides

Titanium tetraiodide, TiI₄, is also an important tetrahalide because it is able to give high purity titanium metal. How? Reversing the reaction of Ti + 2 I₂ → TiI₄ separates pure metal. However, this compound is relatively rare. Additionally, it is insoluble and hydrolyzes in water.  

Fluorides

Fluoride ions play a role in the protective oxide layer of titanium and its alloys; They have a corrosive effect. Titanium will react with fluorine at higher temperatures to form a titanium (IV) halide, called titanium tetrafluoride, TiF₄. This is an insoluble compound that provides a source of titanium for metal production. It is a studied compound that has potential use in the dentistry field, for the treatment of carious lesions. For now, the findings are inconclusive because of the lack of in vivo studies.  This compound has a unique interaction with dental hard tissue; Fluoride may inhibit tooth decay, but high exposure can cause negative health issues because of its corrosive effects. 

Organometallic compounds

Titanocene dichloride, (C₅H₅)₂TiCl₂, is a metallocene. It is a reagent and catalyst used in many synthesis reactions in organic chemistry and organometallic chemistry. It is bright red in color and forms acicular crystals from toluene. Additionally, (C₅H₅)₂TiCl₂ is a precursor to synthesizing titanium (II) derivatives. This compound is important because it provides a source of titanium for the production of titanium dioxide nanostructures. In the future, (C5H5)2TiCl2, may play a vital role in the medical field, as it is currently being studied for its use as an anti-cancer drug. 

Sulfides

While there are different deviations of titanium sulfides, titanium disulfide, TiS2 is the most important. This smelly, yellow-gray powder is unstable and hydrolyzes in water to release hydrogen sulfide, which is a toxic and flammable gas. Furthermore, it is a cathode, or negatively charged electrode, for rechargeable lithium batteries. 

Nitrides

Titanium nitride, TiN is a refractory transition metal. It exhibits high microhardness, is thermodynamically stable, has conductive properties, reduces friction, and has a high melting point. It is extremely useful and acts as a precursor for the production of the corrosion-resistant coating. Many cutting tools, including surgical equipment, are coated with TiN to increase their durability and sharpness. TiN also leaves a pretty, dark gold-colored finish. 

Isolation of the Element Titanium

Titanium is not an easy metal to extract. To help alleviate this problem, William J. Kroll introduced the Kroll process in the 1930s. This process works to extract pure titanium from its ores, such as rutile, on an industrial scale. As discussed, rutile is a polymorph of titanium dioxide, TiO₂. Rutile is first converted into titanium tetrachloride, TiCl₄, by getting heated with chlorine at a dangerously high temperature of about 1000˚C (1832˚F). Once TiCl₄ vapor is achieved, it gets put into a vessel with either magnesium or sodium and goes through a reduction process at a temperature of about 1000˚C. This reduction reaction is very slow and takes about two days. Once pure titanium element is separated, it must cool down, which can take another few more days. Lastly, the mixture gets crushed and combined with hydrochloric acid to remove any remaining reducing agents, and titanium is further purified. It is important to note that this process must take place in an argon atmosphere instead of air to prevent any unwanted reactions, which would result in brittle metal.

Titanium Oxidation States

Titanium is dominantly found in a +4 oxidation state, but can also exhibit oxidation states of +3 and +2. While the  +3 oxidation site is also common, it is not as important as the +4 state. When a titanium compound is in a +4 oxidation state, it is the most stable and no further oxidation reactions can take place; It is considered to be a high oxidation state, and thus, titanium compounds commonly form covalent bonds. Examples of compounds in the +3 and +2 oxidation states include dititanium trioxide, Ti₂O₃, and titanium monoxide, TiO, respectively. 

Physical Properties of Titanium

Melting point: 1943 K; 1670°C; 3038°F 

Boiling point: 3560 K; 3287°C; 5949°F

Density: 4.506 g/cm³

Atomic weight: 47.867

Atomic number: 22

Electronegativity: 1.54

Classification: Transition metal

Natural abundance in the earth’s crust: 0.44%

Electron shell configuration: [Ar] 3d2 4s2

Isotopes: Ti-46, Ti-47, Ti-48, Ti-49, Ti-50

Found naturally in the minerals: Rutile, ilmenite, (rarely) anatase

Toxicity: Low toxicity

Where can I buy “Titanium”?

iTunes! I’m just kidding. Titanium is a fairly pricey metal. From 2003 to 2014, the price per pound for the metal increased from $15.00 to $30.00. In 2018, a metric ton of the metal cost a whopping $4,800.00. Many commonly invest in the valuable metal; It is used to buy and trade stocks in companies that either mine titanium or use it to produce their products. However, titanium can be easily purchased from Amazon and specialty websites and shops.