JEE Class 12 Chemistry: Group 16 Elements (The Chalcogens)

Vocabulary practice flashcards covering JEE Class 12 Chemistry Group 16 syllabus: elemental properties, trends, allotropes of sulfur, dioxygen, ozone, sulfur dioxide, sulfur trioxide, and sulfuric acid.

Group 16 General Outer Electronic Configuration

The valence shell electron arrangement characteristic of all Group 16 elements, represented as $ns^2\,np^4$.

Group 16 Oxidation States

A range of oxidation numbers displayed by chalcogens, extending from $-2$ to $+6$, where oxygen shows mainly $-2$ and sulfur exhibits $-2$, $+2$, $+4$, and $+6$.

Group 16 Hydride Property Trends

Periodic trends down the hydrides ($H_2O$ to $H_2Te$) characterized by decreasing thermal stability, increasing acidic strength, increasing reducing ability, and an anomalously high boiling point for $H_2O$ due to hydrogen bonding.

Brin's Process

An industrial and chemical method formerly employed for the production and separation of pure dioxygen ($O_2$) utilizing barium oxide ($BaO$).

Dioxygen ($O_2$) Physical Properties

A colorless, odorless, and tasteless gas that supports combustion, reacts with almost all metals, and is paramagnetic due to unpaired electrons.

Laboratory Preparation of Dioxygen ($O_2$)

Thermal decomposition of oxygen-rich salts or metal oxides, including $KClO_3$, $Ag_2O$, $HgO$, $PbO_2$, $Pb_3O_4$, $MnO_2$, $KNO_3$, $KMnO_4$, and $K_2Cr_2O_7$, or by heating $PbO_2$ or $MnO_2$ with concentrated $H_2SO_4$.

Silent Electrical Discharge Process

The synthetic method used to convert dioxygen into ozone ($3O_2 \rightarrow 2O_3$) without generating sparks that would thermally decompose the product.

Ozone ($O_3$) Magnetic Property

Diamagnetic nature characterized by all electrons being paired, in contrast to paramagnetic dioxygen ($O_2$).

Stratospheric Ozone Depletion

The breakdown and reduction of stratospheric ozone caused by nitric oxide ($NO$) emitted in the exhaust of supersonic jets and chlorine radicals from freons.

Tailing of Mercury

The loss of the meniscus and adhesion of mercury to glass surfaces upon exposure to ozone ($O_3$), caused by the oxidation of mercury to mercurous suboxide ($Hg_2O$).

Rhombic Sulfur (Alpha Sulfur)

The yellow, crystalline allotrope of sulfur stable at room temperature, insoluble in water, soluble in carbon disulfide ($CS_2$), and obtained by mining from the Earth's crust.

Transition Temperature of Sulfur

The specific temperature ($369\,\text{K}$ or $95.6\,^\circ\text{C}$) at which rhombic ($\alpha$) and monoclinic ($\beta$) sulfur allotropes coexist in dynamic equilibrium.

Allotropic and Physical Forms of Sulfur

Various physical states and amorphous forms of sulfur, including rhombic, monoclinic, plastic sulfur, flower of sulfur, roll sulfur, and milk of sulfur.

Gunpowder Composition

An explosive propellant mixture traditionally composed of sulfur, potassium nitrate ($KNO_3$), and powdered charcoal (carbon).

Sulfur Dioxide ($SO_2$) Physical Properties

A colorless, suffocating gas with the characteristic odor of burning sulfur that is non-combustible and does not support combustion.

Bleaching Action of $SO_2$

A temporary bleaching action that occurs via reduction in the presence of moisture ($SO_2 + 2H_2O \rightarrow H_2SO_4 + 2[H]$), where color is restored upon aerial re-oxidation.

Sulfur Trioxide ($SO_3$) Thermal Decomposition

The endothermic cleavage of sulfur trioxide into sulfur dioxide ($SO_2$) and dioxygen ($O_2$) occurring at temperatures exceeding $800\,^\circ\text{C}$.

Contact Process

The principal industrial manufacturing method for sulfuric acid ($H_2SO_4$), involving the catalytic oxidation of $SO_2$ to $SO_3$ over a vanadium pentoxide ($V_2O_5$) catalyst.

Oil of Vitriol

The traditional, historical name for sulfuric acid ($H_2SO_4$), frequently referred to in chemical industry as the "king of chemicals."

Dehydrating Action of Sulfuric Acid

The powerful ability of concentrated $H_2SO_4$ to remove elements of water ($H_2O$) from organic compounds, converting formic acid ($HCOOH$) to $CO$, oxalic acid to $CO + CO_2$, malonic acid to $C_3O_2$, and sucrose to carbon.

Volatile Acid Displacement by $H_2SO_4$

The laboratory preparation of volatile acids ($HCl$, $HF$, $HNO_3$) by heating their corresponding salts ($NaCl$, $CaF_2$, $NaNO_3$) with non-volatile, high-boiling concentrated sulfuric acid.

Kipp's Apparatus

A classical laboratory glassware apparatus designed to produce controllable, intermittent supplies of toxic gases such as hydrogen sulfide ($H_2S$) via the reaction of iron(II) sulfide ($FeS$) with dilute sulfuric acid ($H_2SO_4$).

Polonium ($Po$)

A highly radioactive, short-lived metallic element of Group 16 having a brief half-life of $7.8\,\text{days}$.

Group 16 Sulfur Minerals

Key naturally occurring sulfur-containing ores, which include gypsum ($CaSO_4 \cdot 2H_2O$), Epsom salt ($MgSO_4 \cdot 7H_2O$), barite ($BaSO_4$), galena ($PbS$), zinc blende ($ZnS$), and copper pyrites ($CuFeS_2$).

Sulfurous Acid ($H_2SO_3$)

A weak, unstable diprotic acid produced when sulfur dioxide dissolves in water ($SO_2 + H_2O \rightarrow H_2SO_3$), possessing marked reducing properties and readily reacting with $O_2$ and $H_2S$.

Oxoacids of Sulfur

A family of sulfur-containing acids with various structural linkages, including $H_2SO_3$, $H_2SO_4$, peroxomonosulfuric acid ($H_2SO_5$), pyrosulfurous acid ($H_2S_2O_5$), pyrosulfuric acid/oleum ($H_2S_2O_7$), peroxodisulfuric acid ($H_2S_2O_8$), and thiosulfuric acid ($H_2S_2O_3$).

Catenation in Group 16

The tendency of identical atoms to form covalent bonds with each other into chains or rings, most prominently demonstrated by sulfur (forming stable $S_8$ rings) due to high $S-S$ bond energy compared to $O-O$.

Anomalous Behavior of Oxygen

Distinct physical and chemical properties of oxygen compared to other Group 16 elements resulting from its small atomic radius, high electronegativity, absence of vacant $d$-orbitals, and strong propensity for multiple bonding.