amphoteric metals - is a simple matter, which structure, chemical and physical properties similar to those of the metallic element group.Metals themselves may not exhibit amphoteric properties, unlike their compounds.For example, oxides and hydroxides of certain metals have dual chemical nature - in certain conditions they behave as acids and alkalis have properties other.
main amphoteric metals - are aluminum, zinc, chromium, and iron.This group elements include beryllium and strontium.
What is amphoteric?
first time this property has been found a long time ago.And the term "amphoteric elements" was introduced into science in 1814, famous chemist L. thenar and J. Gay-Lussac.In those days it was customary chemicals divided into groups that met their basic properties during the reaction.
Nevertheless, a group of oxides and bases has a dual capacity.Under certain conditions, these substances behave like bases, in others, on the contrary, act as acids.That is exactly what originated the term "amphoteric".To conduct such chemicals during the acid-base reaction depends on the conditions of its implementation, the nature of the reactants involved as well as the properties of the solvent.
Interestingly, in vivo amphoteric metals can interact with both the alkali and acid.For example, during the reaction of aluminum sulfate with the acid aluminum sulfate is formed.And at the same reaction with concentrated alkali metal complex salt is formed.
amphoteric base and their basic properties
Under normal conditions, this solids.They are virtually insoluble in water and are considered rather weak electrolytes.
basic method for obtaining such bases - a reaction of a metal salt with a small amount of alkali.The reaction of precipitation should be done slowly and carefully.For example, in the preparation of a zinc hydroxide, zinc chloride tube cautiously added dropwise sodium hydroxide.Each time you need to slightly shake the container to see the white precipitate metal on the bottom of the dish.
with acids and acid oxides amphoteric substances react as bases.For example, the reaction of zinc hydroxide with hydrochloric acid, zinc chloride is formed.
But during the reaction with a base base amphoteric behave like acid.
Furthermore, under strong heating amphoteric hydroxides decompose to form the corresponding amphoteric oxide and water.
most common amphoteric metals: a brief description of
Zinc belongs to the group of amphoteric elements.Although alloys of this material widely used in ancient civilizations in its pure form could be identified only in 1746.
pure metal is a rather delicate matter bluish color.In air, zinc is oxidized rapidly - its surface is dull and covered with a thin oxide film.
zinc exist in nature mainly in the form of minerals - zincite, smithsonite, Calamity.Most known substance - is blende, which consists of zinc sulfide.The biggest deposits of this mineral are in Bolivia and Australia.
Aluminium is today considered the most abundant metals on the planet.Its alloys are used for many centuries, and in 1825 the substance was isolated in pure form.
Pure aluminum is a lightweight metal silver color.It is easily machined and casting.This element has high electrical and thermal conductivity.In addition, this metal is resistant to corrosion.The fact that the surface is covered with a thin, but highly resistant oxide film.
Today, aluminum is widely used in the industry.
