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

Its symbol ‘Fe’ is derived from the latin name ‘Ferrous’. Other elements and the words from which they are derived: Chlorine (Cl) - Greek word ‘chloros’, Carbon (C) - Latin word ‘carbo’, Aluminium (Al) - Latin word 'alumen'.

Metals are electropositive in nature. They generally have 1, 2 or 3 electrons in their valence shells and readily lose these electrons to form positively charged ions (cations). These cations are stable as they acquire noble gas configuration after losing the valence shell electrons.

The number of electron shells in an atom is determined by its electron configuration Germanium (Atomic Number - 32), Arsenic (33), Selenium (34) and Bromine (35) are the elements of Period 4 in the periodic table, which indicates that they have electrons filling up to the fourth energy level (shell). Periods - It is a horizontal row in a Periodic Table.

18 Group

Atomic number : Beryllium. Elements in the group have similar chemical properties. This is because their atoms have the same number of electrons in the highest occupied energy level.
Example - The elements with the atomic number 3 (Lithium) and 11 (Sodium) have the same properties because both elements have the same valence shell configuration.

A measure of an element's ability to combine with other elements by gaining, losing, or sharing electrons to form chemical bonds. The electrons present in the outermost shell of an atom are known as the valence electrons. Valency of Elements - Hydrogen (H₁ ,1), Helium (He₂ ,0), Boron (B₅ , 3), Carbon (C₆ , 4), Sulphur (S₁₆, 2), Potassium (K₁₉, 1).

(transition elements). This block contains the elements of groups 3 to 12 of the periodic table. s-Block - The elements of Group 1 (alkali metals) and Group 2 (alkaline earth metals). p-Block - Consists of non-metals, metalloids and noble gasses. f-Block Consists of two series of lanthanides and actinides and also called inner transition elements.

The elements present (17th group) are Fluorine (F), Chlorine (Cl), Bromine (Br), Iodine (I) and Astatine (At). The periodic table is divided into 18 groups (columns) and 7 periods (rows).
Group 16: Oxygen family (Chalcogens) consists of the elements Oxygen, Sulfur, Selenium, Tellurium and Polonium. Group 18: Noble Gasses (Helium, Neon, Argon, Krypton, Xenon, Radon). Group 1: Alkali metals (Hydrogen, Lithium, Sodium, Potassium, Rubidium, Cesium and Francium).

He discovered it in 1913. Newlands’ Law of Octaves: When elements are arranged by increasing order of atomic mass, he found that every eighth element has properties similar to that of the first. Mendeléev arranged the elements in increasing order of their atomic masses and according to their chemical properties.

The first period contains 2 elements. The second period contains 8 elements. The third period contains 8 elements. Therefore, the first period contains elements with 1−2 atomic numbers. The second period contains elements with 3−10 atomic numbers. The third contains elements with 11 to 18 atomic numbers.