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=== คุณสมบัติทางเคมี ===
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<!--[[ไฟล์:Titanium in water porbiax diagram.png|thumb|left|The [[Pourbaix diagram]] for titanium in pure water, perchloric acid or sodium hydroxide<ref name="medusa">Ignasi Puigdomenech, ''Hydra/Medusa Chemical Equilibrium Database and Plotting Software'' (2004) KTH Royal Institute of Technology, freely downloadable software at [http://www.kemi.kth.se/medusa/]</ref>]]
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The most noted chemical property of titanium is its excellent resistance to corrosion; it is almost as resistant as [[platinum]], capable of withstanding attack by dilute [[sulfuric acid]] and [[hydrochloric acid]] as well as [[chlorine]] gas, chloride solutions, and most organic acids.<ref name="LANL"/> However, it is soluble in concentrated acids.<ref>{{cite journal|title=Pitting Corrosion of Titanium|journal=J. Electrochem. Soc.|volume=141|issue=3|pages=636–642|year=1994|author=Casillas, N.; Charlebois, S.; Smyrl, W. H.; White, H. S.|doi=10.1149/1.2054783}}</ref> The [[Pourbaix diagram]] in the image shows that titanium is actually thermodynamically a very reactive metal.
However, it is slow to react with water and air, because it forms a [[passivation|passive]] and protective oxide coating that protects it from further reaction.<ref name="EBC"/> When it first forms, this protective layer is only 1–2 [[nanometre|nm]] thick but continues to slowly grow; reaching a thickness of 25 nm in four years.<ref name="Emsley2001p453"/>
Titanium readily reacts with oxygen at {{convert|1200|°C|°F}} in air, and at {{convert|610|°C|°F}} in pure oxygen, forming [[titanium dioxide]].<ref name="TICE6th"/> As a result, the metal cannot be melted in open air since it burns before the melting point is reached. Melting is only possible in an inert atmosphere or in a vacuum. At {{convert|550|°C|°F}}, it combines with chlorine.<ref name="LANL"/> It also reacts with the other halogens and absorbs hydrogen.<ref name="HistoryAndUse"/>
Titanium is one of the few elements that burns in pure nitrogen gas, reacting at {{convert|800|°C|°F}} to form [[titanium nitride]], which causes embrittlement.<ref name="titaniumindustry">{{cite book|title=Industrial Applications of Titanium and Zirconium|url = http://books.google.com/books?id=0Adr4zleybgC&pg=PA112|page = 112|first = A. L.|last = Forrest |chapter = Effects of Metal Chemistry on Behavior of Titanium in Industrial Applications}}</ref>
Experiments have shown that natural titanium becomes radioactive after it is bombarded with [[deuterons]], emitting mainly [[positrons]] and hard [[gamma rays]].<ref name="LANL"/>-->
=== สารประกอบ ===
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