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

Reactivity of an element decreases from top to bottom in the given reactivity series. Potassium (K) > Sodium (Na) > Calcium (Ca) > Magnesium (Mg) > Aluminium (Al) > Zinc (Zn) > Carbon (C) > Iron (Fe) > Lead (Pb) > Hydrogen (H) > Copper (Cu) > Silver (Ag) > Gold (Au).

A solar cell, or photovoltaic cell, is an electronic device that converts the energy of light directly into electricity by the photovoltaic effect. By far, the most prevalent bulk material for solar cells is crystalline silicon (c-Si), also known as "solar grade silicon". Silicon (Si, Group 14, Period 3, atomic number 14) - A semiconductor, brittle, metallic luster, exists as a solid at room temperature and pressure.

Their atomic bonding is quite weak, they have only 1 electron in their valence shell, They have body centered cubic structures that have a lot of empty space and this makes metallic bonds weak. Metals are usually very hard but alkali metals are so soft that they can be cut with a knife.
Properties: High melting points, good conductors of heat and electricity, high density, ductile (ability of the material to be stretched into a wire), Malleable (property of substances which allows them to be beaten into flat sheets). Hardest element - Diamond; Lightest metal - Lithium; Mercury is the only metal which is liquid at room temperature.

Limestone is a non-metallic mineral. Limestone is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed principally of calcium carbonate (calcite) or the double carbonate of calcium and magnesium (dolomite). The other three are metallic in nature. Pyrite - also known as fool's gold. It is iron sulfide.

Solubility - It is defined as the maximum amount of a substance that will dissolve in a given amount of solvent at a specified temperature. Reactivity - It is the rate at which a chemical substance tends to undergo a chemical reaction. Malleability - The property of deforming a material on being pressed (or under compressive stress) and spreading in the direction perpendicular to the pressure is called malleability.

A substance or material that allows electricity to flow through it. Non-metal - An element that is generally a poor conductor of heat and electricity, and most properties of non-metals are opposite of metals. Examples - Nitrogen, Fluorine, Sulphur etc. Metal - A solid material that conducts heat and electricity. They are hard, shiny, malleable, and ductile. Examples - Gold, Silver, Aluminium, Copper, Iron, etc.

Anodising is an electrolytic process for producing thick oxide coatings, usually on aluminum and its alloys. Calcination is a process where the air might be supplied in limited quantities, or the ore is heated in the absence of air. Greasing: Process which aims at reducing friction between two moving pieces by injecting a fluid or grease to separate them. Alloys are combinations of metals and other elements.

Anodising: An electrochemical process that converts the metal surface to a decorative, durable and resistant to corrosion. Aluminum ideally suited to anodizing which develops a thin oxide layer when exposed to air. Anodizing reaction: 2Al (Aluminium) + 3H₂O (Water) Al₂O₃ → (Aluminum oxide) + 3H₂ (Hydrogen).

Ore - A deposit of minerals in the Earth's crust. Flux - A chemical that is added to molten metal to connect with impurities that may then be removed. Slag - The glass-like by-product left over after the desired metal has been separated from its raw ore.

Carnotite, Torbernite, Pitchblende is an ore of Uranium. Thorium (Th): (90 atomic number, 232 atomic mass) is a radioactive chemical element. Thorium was discovered in 1828 by the Swedish chemist Jons Jacob Berzelius.