Question

Name two metals which form amphoteric oxide.

Answer 1

Hint:Metal is an element that forms positive ions and has metallic bonds. Alkali metals, alkaline earth metals, transition metals, lanthanides, actinides fall under the category of metals . The amphoteric compound is an ion or molecule that can react both as an acid and a base. Amphoteric nature of a compound depends on the oxidation states of the oxide.

Complete step by step answer:
Now we will discuss the metals forming amphoteric oxide in detail.
Two metals which form amphoteric oxides are Zinc and Aluminium.
Zinc forms zinc oxide $\left( {ZnO} \right)$ which reacts both with acids and with bases.
In acid: $ZnO + {H_2}S{O_4} \to ZnS{O_4} + {H_2}O$
Here zinc oxide reacts with sulphuric acid to give zinc sulphate and water.
In base: $ZnO + 2NaOH + {H_2}O \to N{a_2}\left[ {Zn{{(OH)}_4}} \right]$ Here zinc oxide reacts with a base sodium hydroxide to give sodium zinc hydroxide.

Aluminium forms aluminium oxide $\left( {A{l_2}{O_3}} \right)$ which reacts both with acids and with bases.
 In acid: $A{l_2}{O_3} + 6HCl \to 2AlC{l_3} + 3{H_2}O$
Here aluminium oxide reacts with hydrochloric acid to give aluminium chloride $\left( {AlC{l_3}} \right)$ .
  In base: $A{l_2}{O_3} + 2NaOH + 3{H_2}O \to 2Na\left[ {Al{{\left( {OH} \right)}_4}} \right]$
Here aluminium oxide reacts with a base sodium hydroxide to give hydrated sodium aluminate.

The common example of an amphoteric substance is the hydrogen carbonate ion $\left( {HCO_3^ - } \right)$ .
As base :
$HCO_3^ - + {H_3}{O^ + } \to {H_2}C{O_3} + {H_2}O$
As an acid:
 $HCO_3^ - + O{H^ - } \to CO_3^{2 - } + {H_2}O$

Thus, it can accept or donate a proton.
So, we can say that zinc and aluminium are two metals which form amphoteric oxides.


Note:
We have come across a term metal. So, we will discuss the properties of metals as follows:
Metals are good conductors of electricity and heat.
Metals have high density and melting point.
Metals are shiny (lustrous) in nature.
Metals form basic oxides and amphoteric oxides.
Metals are good reducing agents
Metals are solid at room temperature, an exceptional case is mercury.