Railway Science (Chemistry-Metals , Non-Metals and Alloys) (Part-II)

Different metals show different reactivities towards oxygen. Metals such as potassium and sodium react so vigorously that they catch fire if kept in the open. Hence, to protect them and to prevent accidental fires, they are kept immersed in kerosene oil. At ordinary temperature, the surfaces of metals such as magnesium, aluminum, zinc, lead, etc., are covered with a thin layer of oxide. The protective oxide layer prevents the metal from further oxidation.

The process of applying a protective zinc coating to iron or steel, to prevent rusting. Other methods to prevent rusting of iron - Painting, Oiling, Greasing. Rusting - The interaction of Iron with air and water produces rust. Alloying : It is the method of improving the properties of a metal by mixing the metal with another metal or non-metal.

Ductility : The property of metal by which it can be drawn into wires. Other Examples - Copper, Pure Platinum. Malleability : The property of metals by which they can be beaten into thin sheets. Example - Steel, Aluminium, Copper, Silver.

It is because the melting point of tungsten is very high. Nichrome is used to make the coils used in water heaters. It is also used in heating elements such as hair dryers, toasters, and ovens.

Bronze is an alloy of Copper (Cu) and tin (Sn). Examples of some alloys: Brass - Copper and Zinc. Steel - Iron and carbon. Stainless steel - Iron, Carbon, Chromium and Nickel. Solder - Tin and Lead. German Silver - Copper, Nickel and Zinc. Gunmetal - Copper, Tin and Zinc.

(Aluminium) is extracted by the electrolysis of alumina mixed with molten cryolite. This process is known as the Hoope’s process. In this process, the impure aluminium is collected over the anode and the pure aluminium is obtained on the cathode with a salt of the metal being the electrolyte.

Non-metals have a dull appearance. This is a physical property of non-metals. But iodine is an exception. It occurs as a lustrous/shiny violet crystals.

Aluminium is extracted by the electrolysis of alumina mixed with molten cryolite. This process is known as the Hoope's process. Through this process, the impure aluminium is collected over the anode and the pure aluminium is obtained on the cathode with a salt of the metal being the electrolyte.

Non-metal oxides are acidic in nature while metal oxides are basic in nature. Metals lose electrons to form cations (positive charge) whereas non-metals gain electrons to form anions (negative charge). Metals are good conductors of electricity because of a lot of free electrons, while non-metals are bad conductors of electricity because they have no free electrons.

Its Latin name is Aurum 'gold' and the atomic number is 79. About 2 km long wire can be drawn from one gram of gold. Ductility- The ability of metals to be drawn into thin wires.