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

Nichrome is a family of alloys of nickel and chromium commonly used as resistance wire. It has a high melting point of about 1,400 °C (2,550 °F). Aluminium (Al) Atomic Number 13 (Discovered by Hans Christian Oersted in 1825). Iron (Fe) atomic number 26 and group 8. Copper (Cu) (atomic number 29 , group 11).

Ca (Calcium) > Al (Aluminium) > Cu (Copper) > Hg (Mercury). Reactivity refers to how easily a substance reacts chemically with other substances. Metal - Substance with high electrical conductivity, luster and malleability, which readily loses electrons to form positive ions (cations). Reactivity Factors - atomic radius, nuclear charge, sublevel electrons arrangement and shielding effect. Reactivity of elements increases down the group and decreases from left to right across a period.

Atomic number (82). It is a heavy metal. It is soft and malleable with a low melting point. Reactivity is a measure of how much a substance reacts when it is mixed with another substance. Platinum (Pt) and gold (Au) are the least reactive metals respectively while Potassium (K) and Sodium (Na) are the most reactive metals respectively.

Non-metals - Do not produce heat or electricity, brittle (can not be easily rolled, molding, extruding or pressing), non lustrous. Example - Hydrogen (H), Carbon (C), Nitrogen (N), Oxygen (O), Phosphorus (P), Selenium (Se) etc. Metals - High melting point, good conductor of electricity and heat, high density, malleable and ductile. Example - Aluminum (Al), Zinc (Zn), Copper (Cu), Iron (Fe).

Metals are materials holding or possessing the characteristics of being shiny, hard, fusible, malleable, ductile, etc. Examples - Gold (Au), Silver (Ag), Aluminium (Al), Copper (Cu), Iron (Fe) etc. Metals (Electropositive Nature), lose electrons from their outermost shell in order to become stable and positively charged. Non-metals (Electronegative Nature), gain electrons in order to become stable and negatively charged.

Properties - Metals form basic oxides. Metals are Electropositive in nature because all metals lose electrons from their outermost shell in order to become stable and hence become positively charged. They are Good conductors of heat and electricity.
Non-metals are placed on the right side of the periodic table. Non- Metals are electronegative in nature. Non-metals form acidic oxides. A mixture is a physical combination of two or more substances which are not combined chemically and are mixed in the form of solutions, suspensions and colloids (e.g. seawater, air, ink, cement).

The reaction of Copper- 2Cu + H₂O + CO₂+ O₂ → Cu(OH)2 + CuCO₃ . After the reaction, a mixture of copper carbonate and copper hydroxide is formed which is green in colour.
Corrosion: A natural process that causes the transformation of pure metals into undesirable substances when they react with substances like water or air. Metals colour due to corrosion: Iron (Reddish brown), Silver (black coating), etc. Rusting: The process where iron corrodes due to exposure to the atmosphere.

Graphite is an allotrope of the non-metal carbon which conducts electricity. Allotropes are two or more forms of the same elements that exist in the same physical state (solid, liquid, or gas) but have physical and chemical properties that differ from one another. Non-metals are found in the Periodic Table's top right corner. Diamond is the purest crystalline allotrope of carbon. It has a number of carbons linked together tetrahedrally.

K (Potassium) > Al (Aluminium) > Fe (Iron) > Pb (Lead) > Au (Gold). The number of electrons in the outermost shell of an atom determines its reactivity. Noble gases have low reactivity because they have full electron shells. Halogens are highly reactive because they readily gain an electron to fill their outermost shell. A series in which metals are arranged in the decreasing order of their reactivity is called reactivity series.