Amphoteric compounds, elements, metals

There are five amphoteric elements in the periodic table Be, Al, Zn, Sn, Pb. Also those elements oxides also are amphoteric compounds. Amphoteric elements and compounds react with both acids and bases and give relevant products.

What is amphoterism?

The ability to react as an acid or a base, is known as amphoterism.

In this tutorial,

First, we discuss about amphoteric behavior of amphoteric different elements. Then we study about other amphoteric compounds of transition metals. Then explain some questions of amphoteric properties and compounds.

Amphoteric metals and their position in periodic table

All amphoteric elements are metals and they are located in s, p, d blocks.

  1. Be : s block (IIA group)
  2. Al : p block (IIIA group)
  3. Zn : d block (IIB group)
  4. Sn : p block (IVA group)
  5. Pb : p block (IVA group)

Amphoteric behavior of Be, Al, Zn, Sn, Pb

Now we discuss about amphoteric metals behavior of Be, Al, Zn, Sn, Pb and their oxides.

Amphoteric behavior of Beryllium

Beryllium is a metal of alkaline earth metals. Beryllium reacts with HCl and give beryllium chloride ( BeCl2 ) and H2 gas. Also beryllium reacts with NaOH and give sodium berrylate (NaBeO2.2H2O or Na2[Be(OH)4] ) and hydrogen gas(H2).

Beryllium and sodium hydroxide

Be + NaOH |Beryllium and sodium hydroxide

Beryllium and HCl

Be + HCl |Beryllium and HCl

Amphoteric behavior of Aluminium

Aluminium reacts with both acids and bases to show amphoteric properties.

Aluminium reacts with HCl acid and give aluminium chloride ( AlCl3 ) and hydrogen ( H2 ) gas. Aluminium reacts with NaOH and give NaAlO2 or Na+[Al(OH)4]- which are aqueous solutions.

Aluminium and sodium hydroxide reaction

Aluminium and sodium hydroxide

Aluminium and HCl

Aluminium and HCl

Aluminium hydroxide ( Al(OH)3 ) is also an amphoteric compound.

Amphoteric behavior of zinc

Zinc reacts with both acids and bases to give products.

Zn and HCl reaction

Zn+HCl amphoteric behavior

Zn and NaOH reaction

Zn + NaOH amphoteric behavior

Amphoteric behavior of zinc oxide (ZnO)

ZnO can react as either an acidic or basic oxide and it is therefore known as an amphoteric oxide. ZnO reacts with HCl(aq), NaOH(aq), Na2O(aq).

Zinc oxide and hydrochloric acid reaction

Zinc oxide ( ZnO ) reacts with and hydrochloric acid ( HCl ) and give zinc chloride ( ZnCl2).

ZnO + HCl reaction

Zinc oxide and sodium hydroxide reaction

Zinc oxide ( ZnO ) reacts with sodium hydroxide ( NaOH ) and produce sodium zincate ( Na2ZnO2 ).

ZnO + NaOH + H2O

Zinc oxide and sodium oxide reaction

Zinc oxide ( ZnO ) reacts as an acid with sodium oxide ( Na2O ) and forms the zincate ion [Zn(OH)4]2- complex ion. This reaction is formally equivalent to the reaction without water.

ZnO + Na2O reaction

Amphoteric behavior of zinc hydroxide

Zinc hydroxide ( Zn(OH)2 ) is an amphoteric compound and a white precipitate. It reacts with HCl(aq) acid and give zinc chloride ( ZnCl2 ) aqueous solution. Also Zn(OH)2 reacts with excess NaOH and forms Na2[Zn(OH)4].

Amphoteric behavior of Lead

Lead(Pb) react with HCl and forms lead chloride ( PbCl2(s) ) and hydrogen gas ( H2(g) ). But Pb does not dissolve in concentrated HCl because a surface coating of PbCl2. Pb slowly reacts with cold alkali and rapidly by hot alkali forming plumbates.

Pb and HCl reaction

Pb and HCl, Amphoteric behavior of Lead

Pb and NaOH reaction

Pb and NaOH, Amphoteric behavior of Lead

Amphoteric behavior of Tin

Tin(Sn) react with dilute HNO3 acid to form Sn(NO3)2, NH4NO3 and water. Sn react slowly with cold alkali, but with hot alkali Sn react rapidly for, stannates .

Tin and nitric acid reaction

Tin ( Sn ) reacts with nitric acid ( HNO3 ) and give tin(II) nitrate ( Sn(NO3)2, ammonium nitrate ( NH4NO3 ) and water as products.

Sn and nitric acid, Amphoteric behavior of tin

Tin and sodium hydroxide reaction

Tin reacts with sodium hydroxide to give Sodium stannate ( Na2[Sn(OH)6] )

Sn and NaOH, Amphoteric behavior of tin

Amphoteric behavior of Beryllium ion

Beryllium oxide, Beryllium hydroxide exhibits amphoteric behavior.

Be(OH)2 and OH-

Beryllium hydroxide with bases Amphoteric behavior

Be(OH)2 and H+

Beryllium hydroxide with acids Amphoteric behavior

Amphoteric compounds of d block metals

Amphoteric characteristics of chromium compounds

Some 3d metal compounds such as chromium hydroxide, chromium(III) oxide, ferric oxide has amphoteric characteristics.

Amphoteric properties of chromium hydroxide (Cr(OH)3)

Chromium hydroxide (Cr(OH)3) is an amphoteric compound and a green precipitate. When NaOH(aq) is added that precipitate dissolve and give to [Cr(OH)4] - (aq) solution. Cr(OH)3 reacts with acids.

Amphoteric properties of chromium(III) oxide

Chromium(III) oxide (Cr2O3) is an amphoteric compound. It is green colour and reacts with both acids and bases.

Chromium(III) oxide and NaOH reaction

Cromium(III) oxide and NaOH reaction

Chromium(III) oxide and HCl reaction

Cromium(III) oxide and HCl reaction

Amphoteric behavior of ferric oxide(Fe2O3)

Ferric oxide(Fe2O3) reacts with both acids and basic oxides

Fe2O3 and acids

ferric oxides and acids| Fe2O3 + HCl

Fe2O3 and CaO or Na2CO3

ferric oxide and basic oxides| Fe2O3 + CaO

More points of amphoteric compounds

  • Ga2O3 shows amphoteric characteristics.

Amphoteric compounds, elements, metals summary

Below figure shows the summary of amphoteric compounds such as oxides, hydroxides and amphoteric metals.

Amphoteric compounds, elements, metals

Are all amphoteric elements are metals?

Yes. All amphoteric elements are metals.

Is NaOH amphoteric?

No. Alkali metals' hydroxides, oxides do not show amphoteric properties. Therefore NaOH is not an amphoteric compound.

Related Tutorials of Amphoteric Compounds