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

Krypton (Kr) is a rare, colorless, odorless noble gas (Group 18) with atomic number 36, found in trace amounts in Earth's atmosphere, used in lighting, photography, and lasers for its bright light emission when ionized.

Derived from the Greek word for "hidden," it's chemically inert but forms compounds with fluorine and oxygen, and famously lends its name to Superman's home planet and vulnerability mineral, kryptonite, in fiction.

The maximum number of electrons that can be accommodated in a shell is indicated by the formula 2n² . First shell (K) consists of 2 electrons, the second shell (L) consists of 8 electrons, the third shell (M) consists of 18 electrons, the fourth shell (N) consists of 32 electrons.

The element X with 12 protons in its nucleus is Magnesium. Electronic configuration: 1s² 2s² 2p⁶ 3s² . Since, it has 2 electrons in the valence shell- it belongs to IIA or 2 groups since group number is equal to valence electrons.

The s-block elements of the Periodic Table are those in which the last electron enters the outermost s-orbital. Two groups (1 and 2) belong to the s-block of the Periodic Table.
Group 1 of the Periodic Table consists of the elements: Lithium (3), Sodium (11), Potassium (19), Rubidium (37), Caesium (55) and Francium (87). They are collectively known as the alkali metals.
The elements of Group 2 include beryllium (4), magnesium (12), calcium (20), strontium (38), barium (56) and radium (88). These elements with the exception of beryllium are commonly known as the alkaline earth metals.

The halogen elements are the six elements in Group 17 of the periodic table. Group 17 occupies the second column from the right in the periodic table and contains fluorine (F), chlorine (Cl), bromine (Br), iodine (I), astatine (At), and tennessine (Ts).

Ionization potential is the minimum energy required to remove the most loosely bound electron from an isolated gaseous atom or ion. Liquid elements at standard room temperature and pressure are Bromine (Br) and Mercury (Hg). The elements of group 11 (Cu, Ag, and Au) are called coinage metals .

It belongs to the halogen group (Group 17) on the periodic table, known for their high electronegativity and tendency to gain electrons to form negatively charged ions. Halogen Element: Fluorine (F₉), Bromine (Br₃₅), Iodine(I₅₃), Astatine(At₈₅).

Argon has an atomic number of 18, with electron configuration 2, 8, 8 or [Ne] 3s² 3p⁶. The maximum electrons in the valence shell (outermost shell) is 8, following the Aufbau principle or diagonal rule.

Elements with atomic numbers 11 to 18 (sodium, magnesium, aluminium, silicon, phosphorus, sulfur, chlorine, and argon) all have their first two electron shells filled and are starting to fill their third shell.

The shell which is closest to the nucleus or the first shell is known as K-shell. It is followed by the L-shell, then the M-shell and then the N-shell. The maximum number of electrons occupied by a shell is given by the formula 2n² where, ‘n’ is the shell number. K, L, M, N orbits can accommodate a maximum of 2, 8, 18, 32 electrons respectively