XII-Chemistry Chapter 1: Chemistry of Representative Elements

Vocabulary practice flashcards covering fundamental concepts, periodic trends, industrial processes, and chemical properties from Chapter 1 (Chemistry of Representative Elements) of XII-Chemistry.

Inorganic Chemistry

The branch of chemistry that deals with the study of elements and their compounds, generally obtained from non-living organisms such as minerals.

Organic Chemistry

The branch of chemistry that deals with the study of hydrocarbons (carbon compounds) and their derivatives, excluding $CO$, $CO_2$, carbonates, bicarbonates, and carbides.

Periodic Table

A systematic arrangement of chemical elements based on their atomic number, electronic configuration, and recurring properties.

Groups

The 18 vertical columns of the periodic table containing elements that share similar valence electronic configurations and chemical properties.

Periods

The seven horizontal rows of the periodic table containing elements that possess the same number of electron shells.

Representative Elements

The elements belonging to sub-group A of the periodic table, consisting of s-block and p-block elements.

Transition Elements

The elements belonging to sub-group B of the periodic table, divided into outer transition elements (d-block) and inner transition elements (f-block).

s-Block Elements

Reactive metals in Groups IA and IIA whose valence electrons enter s-orbitals, characterized by general valence configurations of $ns^1$ and $ns^2$.

p-Block Elements

Elements belonging to Groups IIIA through VIIIA whose valence electrons enter p-orbitals, featuring the general valence configuration $ns^2, np^{1-6}$ and comprising metals, non-metals, and metalloids.

d-Block Elements

Outer transition elements located in the middle of the s-block and p-block (Groups IIIB to VIIIB, IB, IIB) where valence electrons enter $(n-1)d$ orbitals, having general configuration $ns^2, (n-1)d^{1-10}$.

f-Block Elements

Inner transition elements placed at the bottom of the periodic table (Lanthanide and Actinide series) in which incoming valence electrons enter $(n-2)f$ orbitals.

Group Trend

The regular, gradual variations observed in the physical and chemical properties of elements as one moves downward through a group in the periodic table.

Atomic Radius

The distance measured from the nucleus of an atom to its outermost electron shell, commonly expressed in picometers ($pm$).

Shielding Effect (Screening Effect)

The decrease in the electrostatic force of attraction exerted by the nucleus on the valency electrons caused by the repulsive presence of electrons in the inner intervening shells.

Poor Shielding Effect

The phenomenon in which inner d- or f-orbitals (due to diffuse electron density) fail to shield outer electrons effectively, leading to an increased effective nuclear charge, smaller atomic radii, and elevated ionization energies.

Ionization Energy (I.E)

The minimum quantity of energy required to remove an electron completely from the valence shell of an isolated gaseous atom in its ground state.

Lanthanide Contraction

The progressive reduction in atomic size across the lanthanide elements, causing period 6 elements like Lead ($Pb$) to have nearly the same atomic radius as period 5 elements like Tin ($Sn$), resulting in Lead having a higher ionization energy.

Electronegativity (E.N)

The tendency or relative power of an atom in a molecule to attract a shared pair of bonding electrons towards itself.

Electrical Conductivity

A measurement of the intrinsic ability of a substance to transmit electric current, directly proportional to atomic size and the availability of mobile electrons.

Oxidation State

A formal numerical value assigned to an element in a chemical compound or combined state representing the apparent number of electrons lost or gained.

Flame Test

A qualitative analytical technique used to detect and identify alkali and alkaline earth metal ions based on the characteristic emission wavelengths and colors produced when heated in a flame.

Caustic Soda

The common commercial name for sodium hydroxide ($NaOH$), a corrosive, highly water-soluble white solid manufactured by the Castner-Kellner process.

Castner-Kellner Cell

A large rectangular steel electrolytic apparatus consisting of titanium anodes and a circulating mercury cathode, used for the industrial production of sodium hydroxide from brine.

Denuder

A chamber packed with graphite blocks in the Castner-Kellner cell where sodium amalgam reacts with water to yield pure sodium hydroxide solution and hydrogen gas while releasing mercury.

Bleaching Powder

A yellowish-white amorphous substance chemically known as calcium hypochlorite with the formula $Ca(OCl)_2$, used industrially as a disinfectant and bleaching agent.

Hasenclever Process

A commercial manufacturing process wherein dry slaked lime ($Ca(OH)_2$) is fed into rotating horizontal cylinders and reacted countercurrently with chlorine gas to form bleaching powder.

Oil of Vitriol

The archaic historical term for sulphuric acid ($H_2SO_4$), derived from its early historical preparation by the distillation of green vitriol.

Contact Process

The primary modern industrial method for manufacturing sulphuric acid by burning sulphur to $SO_2$, oxidizing it to $SO_3$ over a $V_2O_5$ catalyst, absorbing it into concentrated acid, and diluting.

Arsenic Purifier

A purification unit in the Contact Process plant that utilizes ferric hydroxide ($Fe(OH)_3$) to absorb and eliminate arsenic oxide ($As_2O_3$) vapours, preventing catalyst deactivation.

Oleum

Pyrosulphuric acid ($H_2S_2O_7$), an intermediate fuming liquid produced during the Contact Process by absorbing sulphur trioxide into concentrated sulphuric acid.

Testing Box

A diagnostic chamber in the Contact Process where a beam of light is passed through the gas mixture to detect colloidal dust and acid fog via the Tyndall effect before entering the catalyst tower.

Structure of Sulphuric Acid

A covalent tetrahedral molecular structure where a central sulphur atom is bound to two hydroxyl ($-OH$) groups and two oxo ($=O$) atoms.

Dibasic Acid

An acid, such as sulphuric acid ($H_2SO_4$), that contains two replaceable hydrogen atoms per molecule and ionizes in two sequential stages to donate two protons.

Sulphonation

An electrophilic substitution reaction in which a hydrogen atom on an aromatic ring is replaced with a sulphonic acid group ($-SO_3H$) upon reacting with concentrated sulphuric acid.

Bond Enthalpy (in Halogens)

The quantity of energy required to dissociate one mole of halogen-halogen diatomic covalent bonds ($X-X$) into individual gaseous atoms.

Auto-Oxidizing and Reducing Agent

A substance like elemental chlorine ($Cl_2$) that undergoes simultaneous self-reduction (to form $HCl$) and oxidation (to form $HOCl$) when reacting with water.

Diagonal Relationship

The remarkable similarity in chemical and physical properties shared by certain pairs of diagonally adjacent elements in the second and third periods of the periodic table ($Li$ with $Mg$, $Be$ with $Al$, $B$ with $Si$).

Borax

An essential industrial boron compound with the formula $Na_2B_4O_7 \times 10H_2O$, widely employed in cleaning, laundry, cosmetics, and as a welding flux.

Alum

A hydrated double sulphate salt with the formula $K_2SO_4 \times Al_2(SO_4)_3 \times 24H_2O$, used for water purification, leather tanning, fire extinguishers, and as an antiseptic styptic.