The p-Block Elements: Groups 15, 16, 17, and 18

Vocabulary practice flashcards covering fundamental terms, processes, and chemical structures across Groups 15 to 18 of the p-block elements.

Chile saltpetre

The naturally occurring mineral form of sodium nitrate ($NaNO_3$) found in the earth's crust as a source of nitrogen.

Indian saltpetre

The naturally occurring mineral form of potassium nitrate ($KNO_3$) found in the earth's crust.

Fluorapatite

A phosphate mineral belonging to the apatite family with the formula $Ca_9(PO_4)_6 \times CaF_2$, forming the main component of phosphate rocks.

Inert pair effect

The reluctance of the valence $s$-electrons to participate in chemical bonding in heavier $p$-block elements, which increases the stability of lower oxidation states ($+3$ in Group 15; $+4$ in Group 16) over higher oxidation states down the group.

Haber's process flow chart

The industrial setup used to manufacture ammonia from $N_2$ and $H_2$ gas, using a compressor operating at $20\,MPa$, a catalyst bed of iron oxide with $Al_2O_3 + K_2O$ at $700\,K$, a cooling/liquefaction unit, and a gas recirculation pump.

Ammonia ($NH_3$) molecular structure

A trigonal pyramidal molecule with a nitrogen atom at the apex having three bond pairs and one lone pair of electrons, with an $N-H$ bond distance of $101.7\,pm$ and an $H-N-H$ bond angle of $107.8^\circ$.

Nitric acid ($HNO_3$) molecular structure

A planar molecule in the gaseous state featuring an $O-H$ bond length of $96\,pm$, an $N-O$ single bond length of $140.6\,pm$, an $N-O$ terminal bond length of $121\,pm$, an $H-O-N$ angle of $102^\circ$, and an $O-N-O$ angle of $130^\circ$.

Brown ring test

A confirmatory test for nitrate ions based on the reduction of $NO_3^-$ to $NO$ by $Fe^{2+}$, which combines with hydrated ferrous ions to form the brown-coloured coordination complex $[Fe(H_2O)_5(NO)]^{2+}$ at the interface of the test solution and concentrated $H_2SO_4$.

White phosphorus

A translucent, waxy, poisonous allotrope of phosphorus that glows in the dark (chemiluminescence), is soluble in $CS_2$, and consists of discrete tetrahedral $P_4$ molecules with an internal bond angle of $60^\circ$.

Red phosphorus

An iron-grey lustrous, non-poisonous, and odourless allotrope of phosphorus obtained by heating white phosphorus at $573\,K$ in an inert atmosphere, possessing a polymeric structure of interconnected $P_4$ tetrahedra.

Phosphine ($PH_3$)

A colourless, highly poisonous gas with a rotten fish smell prepared by heating white phosphorus with concentrated $NaOH$ solution in an inert atmosphere of $CO_2$.

Holme's signals

A maritime signaling application that utilizes containers of calcium carbide and calcium phosphide pierced and thrown into the sea, evolving acetylene and phosphine gases that spontaneously catch fire.

Chalcogens

The elements of Group 16 (oxygen, sulphur, selenium, tellurium, and polonium), named after the Greek word for brass due to their frequent association with copper ores.

Transition temperature of sulphur

The temperature of $369\,K$ at which both rhombic sulphur ($\alpha$-sulphur) and monoclinic sulphur ($\beta$-sulphur) are stable in equilibrium.

Ozonised oxygen

The mixture of oxygen containing approximately $10\%$ ozone produced when a slow, dry stream of oxygen is subjected to a silent electrical discharge.

Amphoteric oxide

A metal oxide, such as $Al_2O_3$, that displays dual chemical characteristics by reacting with both acids and alkalies to form salts.

Neutral oxide

An oxide that exhibits neither acidic nor basic properties when brought into contact with water, acids, or bases (e.g., $CO$, $NO$, and $N_2O$).

Contact process

The industrial process used to manufacture sulphuric acid ($H_2SO_4$) via the catalytic oxidation of $SO_2$ to $SO_3$ over a $V_2O_5$ catalyst at $720\,K$ and $2\,bar$, followed by absorption in $H_2SO_4$ to form oleum.

Oleum

Pyrosulphuric acid ($H_2S_2O_7$), an oily intermediate obtained by absorbing sulphur trioxide ($SO_3$) into concentrated sulphuric acid ($H_2SO_4$).

Deacon's process

The industrial manufacture of chlorine gas ($Cl_2$) by the catalytic oxidation of hydrogen chloride gas by atmospheric oxygen at $723\,K$ in the presence of a $CuCl_2$ catalyst.

Aqua regia

A corrosive liquid mixture composed of three parts concentrated hydrochloric acid ($HCl$) and one part concentrated nitric acid ($HNO_3$) by volume, used for dissolving noble metals such as gold and platinum.

Bleaching powder

A solid compound obtained by the action of chlorine gas on dry slaked lime ($Ca(OH)_2$), having the composite formula $Ca(OCl)_2 \times CaCl_2 \times Ca(OH)_2 \times 2H_2O$.

Interhalogen compounds

Covalent, diamagnetic compounds formed by the direct combination of two distinct halogens, conforming to the general formulas $XX'$, $XX'_3$, $XX'_5$, and $XX'_7$, where $X$ is the larger, more electropositive halogen.

Bartlett's compound

The red ionic compound formulated as $Xe^+[PtF_6]^-$, synthesised by Neil Bartlett in 1962, representing the first recognized chemical compound of a noble gas.

Ostwald's process

The commercial method for the large-scale manufacture of nitric acid ($HNO_3$) by catalytic oxidation of ammonia with atmospheric oxygen over a $Pt/Rh$ gauge catalyst at $500\,K$ and $9\,bar$.