10th Class Science Metals and Non-metals / धातु और अधातु Metals and Non-metals

Metals and Non-metals

118 elements are identified of which the first 94 occur naturally on Earth with the remaining 24 being synthetic elements. Metals and non-metals are characterized by their physical and chemical properties.

Characteristics of Metals

• Metals have tendency to lose electrons.
• Metals are strong and tough.
• Metals have high melting and boiling point.
• Most of the metals are malleable or can be changed into thin sheets. For example, aluminum can be drawn into thin sheets.
• Metals are ductile or can be drawn out into thin wires. For example, copper can be drawn into wire.
• Metals are good conductor of electricity and heat.
• Metals are solids at room temp except mercury, which is a liquid.
• Metals are lustrous.
• Metals tend to have low ionization energies. In other words they gets oxidized when they undergo chemical reactions.
• Metals form compounds with non-metals that are ionic in nature.
• Most metal oxides are basic oxides. They dissolve in water to form metal hydroxides.
• Metal oxide \[+\] water \[\to \] metal hydroxide

\[N{{a}_{2}}O(s)+{{H}_{2}}O(l)\to 2NaOH(aq)\]

\[CaO(s)+{{H}_{2}}O\,\,(l)\to Ca{{(OH)}_{2}}(aq)\]

• Metal oxides exhibit their basic chemical nature by reacting with acids to form salts and water:
• Metal oxide + acid \[\to \] salt + water

\[MgO(s)+HCl(aq)\to MgC{{l}_{2}}(aq)+{{H}_{2}}O(l)\]

\[NiO(s)+{{H}_{2}}S{{O}_{4}}(aq)\to NiS{{O}_{4}}(aq)+{{H}_{2}}O(l)\]

Characteristics of Non Metals

• Nonmetals have tendency to gain electrons.
• Nonmetals are brittle. They are neither malleable nor ductile.
• Nonmetals are non-lustrous.
• Nonmetals are poor conductors of heat and electricity.
• Nonmetals have melting point lower than metals.
• Nonmetals, gain electrons on reacting with metals to attain noble gas electron configuration and become anions.
• Most nonmetal oxides are acidic oxides. These acidic oxides dissolve in water to form acids.

Non metal oxide + water \[\to \] acid

\[C{{O}_{2}}(g)+{{H}_{2}}O(l)\to {{H}_{2}}C{{O}_{3}}(aq)\]

     (Carbonic acid)

• Nonmetal oxides can combine with bases to form salt and water.

Metalloids

Metalloids have properties intermediate between the metals and nonmetals. Silicon for example appears lustrous, but is neither malleable nor ductile but is brittle which the characteristic of some nonmetals. Metalloids are also useful in the semiconductor industry.