Some inorganic functions do not receive as much attention in textbooks and even during the classes of some teachers, such as carbides and hydrides. In this text, let's do it differently, we'll explain some important details about the inorganic function called hydride.
You hydrides they are binary inorganic compounds (they have two chemical elements) that present in their constitution the hydrogen element accompanied by any other chemical element. The most important detail is that hydrogen almost always has a nox equal to -1, which makes it, in some hydrides, the most electronegative element. The water (H2O) and ammonia (NH3) are examples that escape this occurrence.
To name a hydride, the naming rule is quite simple:
Hydride+in+name of element that accompanies hydrogen
See some examples of hydride nomenclature:
NaH = Sodium hydride
KH = Potassium hydride
CaH2 = calcium hydride
AlH3 = aluminum hydride
SiH4 = silicon hydride
It is very common to find hydrides of three different classifications: ionic, molecular and metallic. See the characteristics of each of these types:
a) Ionic hydride:
Features a metallic element accompanying hydrogen. The most common metallic elements are the alkali, alkaline earth metals (except beryllium and magnesium), gallium, indium, thallium and the lanthanides.
Examples of ionic hydrides:
NaH = Sodium hydride
KH = Potassium hydride
CaH2 = calcium hydride
Ionic hydrides have the following characteristics:
Solids;
High melting point;
Conduct electric current (when in liquid state);
Most decay before reaching their melting point;
They are very reactive with water (In this reaction they always form an inorganic base accompanied by hydrogen gas). See an example of this reaction:
Reaction equation of a sodium hydride with water
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b) Molecular (or covalent) hydride
They are hydrides formed by the combination of hydrogen with elements from groups 13 to 17 (families: boron, nitrogen, chalcogens and halogens). Elements with low electropositivity, such as beryllium and aluminum, even being metals, form molecular hydrides.
Examples of molecular hydrides:
AlH3 = aluminum hydride
SiH4 = silicon hydride
H2O = Oxygen Hydride
Its main features are:
They can be solid, liquid or gaseous;
They do not carry electrical current;
They have a low melting and boiling point;
They are volatile at room temperature;
They have weak chemical bonds.
c) Metal or interstitial hydride
Hydrides that have a transition metal (element that presents the d sublevel as more energetic/B families) following the hydrogen. They are called interstitials because the hydrogen atom often occupies interstices in the solid structure of the metal, as in the following representation:
hydrogen atom surrounded by titanium atoms
Between the main uses of hydrides, which are solid and good conductors of electricity, we have:
Storage and transport of solid state hydrogen;
Aluminum and lithium hydrides are reducing agents in organic syntheses (addition of hydrogens to organic compounds);
Platinum hydrides are used in organic halogenation reactions (addition of chlorine, fluorine, bromine or iodine atoms) to olefins (alkenes, hydrocarbons with a double bond).
Manufacture of rechargeable batteries;
Manufacture of refrigerators;
Manufacturing of temperature sensors.
Model of a temperature sensor that uses hydride in its operation
By Me. Diogo Lopes Dias
Would you like to reference this text in a school or academic work? Look:
DAYS, Diogo Lopes. "Hydrides"; Brazil School. Available in: https://brasilescola.uol.com.br/quimica/hidretos.htm. Accessed on June 28, 2021.
Base Nomenclature, Aqueous Solution, Ionic Dissociation, Cation, Anion, Sodium Hydroxide, Aluminum Hydroxide, Iron Hydroxide, Copper Hydroxide, Ferric Hydroxide, Calcium Hydroxide.
