Railway Science (Chemistry-Periodic Table) (Part-III)

Graphite (allotrope of Carbon): It is a hexagonal crystal structure. It is used in making pencils and lubricants. It is a good conductor of heat and electricity. Its high conductivity makes it useful in electronic products such as electrodes, batteries and solar panels. It occurs naturally in metamorphic rocks.

Protium (The most common hydrogen isotope with an abundance of more than 99.98%) - An isotope of hydrogen that is composed of one proton and one electron, so it has no neutrons in its nuclei. Isotopes of hydrogen (H) - Protium (¹ ₁H), Deuterium (² ₁H), and Tritium (³ ₁H).

Silica (Silicon dioxide) is not an element, rather it is a compound that is composed of silicon and oxygen atoms. Chemical formula of silica - SiO₂ . Graphite (Gr) - A chemical element that is made up of carbon.
Germanium (Ge) - A chemical element which acts as a Metalloid. Silicon (Si) - The most abundant element in The Earth's crust.

Electrons present in the outer shells of an atom are called valence electrons (s and p electrons in the outermost shell). According to Bohr Bury Scheme, the outermost shell of an atom can accommodate a maximum of 8 electrons. Maximum number of electrons that can be accomodated in different shells are (2n²) - K shell (2), L shell (8), M shell (18), N shell (32).

Noble gases (group 18 elements of Periodic Table) are chemically inert with low reactivity due to stable electronic configuration (8 valence electrons in Outermost shell).

Rhodium (Rh, atomic number - 45) is a silver-white metallic element that is highly reflective and resistant to corrosion. It was discovered in 1803 by William Wollaston.

Radon - highly radioactive noble gas that arises from the radioactive decay of radium, thorium and uranium containing minerals.

(Os) - It is used in certain electrical contacts and fountain pen nibs. Atomic number - 76. Mercury (used in thermometers, barometers) - The only metal that is liquid at standard conditions for temperature and pressure.
Lead (used in plumbing, and batteries due to its corrosion resistance and low melting point) - Primarily obtained from the mineral galena (lead sulfide). Platinum (used in the production of jewelry, laboratory equipment) - It is a dense, malleable, and highly valued precious metal.

The formula for water is H₂O. Each molecule contains 2 hydrogen atoms and 1 oxygen atom. Relative atomic masses: Hydrogen (H) = 1, Oxygen (O) = 16. The molecular mass of water = (atomic mass of hydrogen x 2) + atomic mass of oxygen. The molecular mass of water = (2 × 1) + 16 = 18.

Atomic number is the number of protons in the nucleus of an atom, which is characteristic of a chemical element and determines its place in the periodic table. J. J. Thomson - electrons (1897). Ernest Rutherford - protons (1917) James Chadwick - neutrons (1932) whereas neutrons were theorized by Ernest Rutherford in 1920.