can anyone provide me note of chapter metal and non metal
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Answer:
Alloys
Alloys are homogeneous mixtures of metal with other metals or nonmetals. Alloy formation enhances the desirable properties of the material, such as hardness, tensile strength and resistance to corrosion.
Examples of a few alloys –
Brass: copper and zinc
Bronze: copper and tin
Solder: lead and tin
Amalgam: mercury and other metal
Corrosion
Gradual deterioration of material usually a metal by the action of moisture, air or chemicals in the surrounding environment.
Rusting:
4Fe(s)+3O2(from air)+xH2O(moisture)→2Fe2O3. xH2O(rust)
Corrosion of copper:
Cu(s)+H2O(moisture)+CO2(from air)→CuCO3.Cu(OH)2(green)
Corrosion of silver:
Ag(s)+H2S(from air)→Ag2S(black)+H2(g)
For More Information On Corrosion of Metals, Watch The Below Video:
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Prevention of Corrosion
Prevention:
1. Coating with paints or oil or grease: Application of paint or oil or grease on metal surfaces keep out air and moisture.
2. Alloying: Alloyed metal is more resistant to corrosion. Example: stainless steel.
3. Galvanization: This is a process of coating molten zinc on iron articles. Zinc forms a protective layer and prevents corrosion.
4. Electroplating: It is a method of coating one metal with another by the use of electric current. This method not only lends protection but also enhances the metallic appearance.
Example: silver plating, nickel plating.
5. Sacrificial protection: Magnesium is more reactive than iron. When it is coated on the articles made of iron or steel, it acts as the cathode, undergoes reaction (sacrifice) instead of iron and protects the articles.
Physical Properties
Physical Properties of Metals
● Hard and have a high tensile strength
● Solid at room temperature
● Sonorous
● Good conductors of heat and electricity
● Malleable, i.e., can be beaten into thin sheets
● Ductile, i.e., can be drawn into thin wires
● High melting and boiling points (except Caesium (Cs) and Gallium (Ga))
● Dense, (except alkali metals). Osmium – highest density and lithium – least density
● Lustrous
● Silver-grey in colour, (except gold and copper)
Non-Metals
Nonmetals are those elements which do not exhibit the properties of metals.
Physical Properties of Nonmetals
Occur as solids, liquids and gases at room temperature
Brittle
Non-malleable
Non-ductile
Non-sonorous
Bad conductors of heat and electricity
Exceptions in Physical Properties
Alkali metals (Na, K, Li) can be cut using a knife.
Mercury is a liquid metal.
Lead and mercury are poor conductors of heat.
Mercury expands significantly for the slightest change in temperature.
Gallium and caesium have a very low melting point.
Iodine is non-metal but it has lustre.
Graphite conducts electricity.
Diamond conducts heat and has a very high melting point.
Explanation:
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