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

Metals and Non - metals

There are about 118 elements, from which 92 are naturally occurring. 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, aluminium 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 from 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 ice 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

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

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

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

(carbonic acid)

• Non -metal oxides can combine with bases to form salt and water.

Metalloids

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