Thulium chloride or thulium trichloride is the chemical compound

Chemical compound

A chemical compound is a pure chemical substance consisting of two or more different chemical elements that can be separated into simpler substances by chemical reactions. Chemical compounds have a unique and defined chemical structure; they consist of a fixed ratio of atoms that are held together...

 composed of thulium

Thulium

Thulium is a chemical element that has the symbol Tm and atomic number 69. Thulium is the second least abundant of the lanthanides . It is an easily workable metal with a bright silvery-gray luster...

 and chlorine

Chlorine

Chlorine is the chemical element with atomic number 17 and symbol Cl. It is the second lightest halogen, found in the periodic table in group 17. The element forms diatomic molecules under standard conditions, called dichlorine...

 with the formula

Chemical formula

A chemical formula or molecular formula is a way of expressing information about the atoms that constitute a particular chemical compound....

 TmCl₃. It forms yellow crystals. Thulium(III) chloride has the YCl₃

Yttrium(III) chloride

Yttrium chloride is an ionic compound of yttrium and chlorine. It is a salt that is solid at room temperature, highly soluble in water, and deliquescent...

 (AlCl₃) layer structure with octahedral thulium ions.

Reactions

The hydrated

Water of crystallization

In crystallography, water of crystallization or water of hydration or crystallization water is water that occurs in crystals. Water of crystallization is necessary for the maintenance of crystalline properties, but capable of being removed by sufficient heat...

 form of thulium(III) chloride can be obtained by adding thulium(III) oxide

Thulium(III) oxide

Thulium oxide is a pale green solid compound, with the formula Tm2O3. It was first isolated in 1878 from an impure sample of erbia by Per Teodor Cleve, who named it thulia....

 to concentrated hydrochloric acid

Hydrochloric acid

Hydrochloric acid is a solution of hydrogen chloride in water, that is a highly corrosive, strong mineral acid with many industrial uses. It is found naturally in gastric acid....

. Thulium(III) chloride reacts with strong bases

Base (chemistry)

For the term in genetics, see base A base in chemistry is a substance that can accept hydrogen ions or more generally, donate electron pairs. A soluble base is referred to as an alkali if it contains and releases hydroxide ions quantitatively...

to make thulium(III) oxide.