10th, Sci I, Metallurgy I

 

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Some points in science are to be remembered for a long life. The difference between metals and non-metals is evergreen.

In fact  any differences should be written as shown above. But here we are going to see information in the form of points.

First, we learn the point of metal.

1. Physical state:- Generally metals are in solid state except Mercury (Hg).

2. Metals shows malleability   (making sheets) and ductility (making wires) property.

3. Metals are good conductors of heat and electricity. The reason behind is that in the last orbit of metals the electrons which are present are in a free state.

4. Metals are shiny.  

5. Metals are generally hard except group 1 they can be cut with the help of a knife.

6. Melting point (MP)  and boiling point (BP) of metals are generally high.

7. Sonority:- Metals make a ringing sound when we strike them by hammer. This property of metals make a ringing sound is called sonority.

* Chemical properties of metal

1. Metals easily loose electron and make positive ions ( cations).

2. Some metals react with oxygen which is present in air and form metal oxide. Metal oxides are basic in nature.

3. Some metals react with water to form metal hydroxide . In this process hydrogen gas is liberated.

4. Metals react with acid to form metal salt and hydrogen gas is liberated.

5. Some metals react with nitric acid to form nitrate salts of metals.

6. Some metals react with salts of other metals, here displacement reaction takes place more reactive element displaces less reactive elements.

7. When metal reacts with non- metal to form metal salts.

🎷Physical properties of nonmetals 

1. Physical state :- generally nonmetals are solid  and in gaseous state, exception is mercury,  it is in liquid state.

2. Non metal does not show malleability and ductility properties.

3. Nonmetals are bad conductors of heat and electricity.

4. Nonmetals do not possess luster, except  iodine (I).

5. Nonmetals are brittle.

6. The Melting point and boiling point of nonmetals are low.

7. Nonmetals do not show Sonority properties.

* Chemical properties of nonmetal.

1. Non metals easily accept electron and make negative ions ( anions)

2. Generally nonmetals react with oxygen to form acidic oxides of that element.

 3. Generally, nonmetals do not react with water but halogens show such type of reaction.

 4.Generally nonmetals do not react with dilute acids. Only halogens show such type of reactions.

 5.Nonmetals react with hydrogen under certain conditions such as temperature, pressure, catalyst etc.

* Corrosion of metals.

Corrosion of iron means resting is a big problem for us. Corrosion is the gradual deterioration of metal.Corrosion means erosion, wear and tear/ damage of metal.

Many people only know that iron corrodes, but corrosion of silver, aluminum, and copper they also corrode.

1. When silver is exposed to air it reacts with hydrogen sulphide/sulfide H2S gas to form blackish silver sulphide Ag2S.

* Aluminium reacts with atmospheric oxygen to form a white layer of Aluminium oxid(.

* Copper reacts with carbon dioxide (CO2) in moist air to form greenish copper carbonate CuCO3.

* iron reacts with moist air and reddish iron oxide is formed.

Fe2O3.H2O.

Prevention of corrosion.

1. If we prevent the contact of metal with moisture and oxygen in air by applying on metal then we will stop corrosion.

2. If we apply a layer of oil , paint , grease on a metal surface then we will prevent corrosion of metal.

If non correctable metal is coated on carrodable metal then it is full to stop corrosion.

3. Galvanizing

In the process of Galvanizing a thin layer of zinc Zn is applied to prevent corrosion of iron or steel.

Ex. Pins, shining iron nails.

4. Tinning

A layer of the molten tin is deposited on metal like a copper or brass vessel is called tinning. It is also called as *kalhaee* 

5. Anodization

Metals like copper Cu , aluminium Al are coated with a thin and strong layer of their oxides by means of electrolysis is called as anodization.

Ex. Anodized pressure cooker.

6. Electroplating

List reactive metal is coated on a more reactive metal by electrolysis is called electroplating example - 

1. silver plated spoons , 
2. gold plated ornaments.

7. Alloying 

The homogeneous mixture formed by mixing a metal with other metals or nonmetals or metal and non-metal in a certain proportion is called an alloy.

Ex. 

• Stainless still is made up of iron Fe - 74 8 % , chromium Cr- 18 %, carbon C - 8%.
• Bronze is made from copper Cu - 90%, tin Sn- 10%.
• Brass is made from copper Cu -60%, zink Zn - 40%

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