Railway Science (Chemistry-Miscellaneous)

Silicon forms hyper-reactive long-chain compounds due to its larger atomic size, resulting in weaker Si-Si bonds. This makes silicon compounds more prone to reacting with other substances, leading to their high reactivity.
Silicon belongs to the same family of elements as Carbon in the periodic table, but its chemical reactivity differs significantly from that of similar carbon compounds. The silicon atom is larger than the carbon atom. The Si-Si bond is also longer and weaker than the C-C bond.

Nitrogen molecule is diatomic and contains a triple bond between two N atoms. Nitrogen (N) - Atomic number : 7. Nitrogen is a nonmetal and the lightest member of group 15 of the periodic table, often called the pnictogens.

Sodium chloride (NaCl, Table salt), is an ionic compound, representing a 1:1 ratio of sodium and chloride ions. Its boiling point is 1,465 °C.
Lithium chloride (LiCl) is a typical ionic compound, although the small size of the Li⁺ ion gives rise to properties not seen for other alkali metal chlorides, such as extraordinary solubility in polar solvents and its hygroscopic properties. Its boiling point is 1,382 °C.

The carbon atom has 4 electrons in its valence shell 2s² 2p² . The structure of CO₂ is O = C = O, which means carbon is linked to each oxygen by a double bond. So, carbon shares a total of two pairs of electrons to bond with the two oxygen atoms. The CO₂ molecule has a linear geometry as carbon uses sp - hybridised orbitals to form one sigma bond with each oxygen.

China dish is a round bottomed crucible shaped dish which is made of porcelain used for the chemical reactions. China dish is very delicate in appearance only, as it is known for its great strength and resistance to chipping, which results from a high firing temperature.

A covalent bond is a chemical bond that involves the sharing of electrons to form electron pairs between atoms. Properties of Covalent Compounds: The covalent compounds exist as gasses or liquids or soft solids; melting and boiling points are generally low; insoluble in water but dissolve in organic solvents; non-conductors of electricity in solid, molten or aqueous states. Examples - Ammonia (NH₃), Oxygen (O₂), Methane (CH₄) etc.

Organic compound - Contains carbon covalently bound to other atoms, especially Carbon-Carbon (C-C) and Carbon-Hydrogen (C-H) (hydrocarbons). General Characteristics - Contain complex structure, high molecular weights. Ernest Rutherford postulated the nuclear structure of the atom, discovered alpha and beta rays, and proposed the laws of radioactive decay. John Dalton (introduced atomic theory and researched color blindness).

(CH₃CH₂COOH): A naturally occurring carboxylic acid. Uses - Antifungal agent in food. It is present naturally at low levels in dairy products; (Crystal structure:- Monoclinic).

Electrovalent bonds (ionic bond) - Electrostatic force of attraction between oppositely charged ions chemical compounds. It is formed between metals and non-metals. Example: Sodium chloride (NaCl), Lithium carbonate (Li₂CO₃) and ammonium phosphate (NH₄)₃ PO₄ .
Properties - Strongest of all the bonds, most reactive and high melting and boiling point. Conduction - Process by which heat or electricity passes through a material. Occurs in solids, liquids and gases.

Baking soda {Sodium bicarbonate, (NaHCO₃)} begins to break down into sodium carbonate (Na₂CO₃), water (H₂O), and carbon dioxide (CO₂) at temperatures above 176°F (80°C).
Carbon dioxide and water both become gaseous when exposed to heated temperatures. 2NaHCO₃ → Na₂CO₃ + H₂O + CO₂ .
Washing soda (Sodium carbonate decahydrate - Na₂CO₃ .10H₂O) - The production involves the recrystallization of sodium carbonate.