Group 15 - The Pnictogens Lecture 6 Flashcards

Vocabulary-style flashcards covering the properties, allotropes, oxides, and compounds of Group 15 elements and Boron-Nitrogen analogues.

Pnictogens

The name for Group 15 elements, which include Nitrogen ($N$), Phosphorus ($P$), Arsenic ($As$), Antimony ($Sb$), and Bismuth ($Bi$).

Nitrogen Allotrope

Exists as the discrete dinitrogen ($N_2$) molecule characterized by an exceptionally strong triple bond.

White Phosphorus

A highly reactive allotrope of phosphorus consisting of discrete tetrahedral $P_4$ molecules.

Red Phosphorus

A polymeric structure of phosphorus also known as Hittorf's form.

Black Phosphorus

The most stable phosphorus allotrope, which exists in orthorhombic, rhombohedral, and cubic polymorphs.

Bismuth Surface

Often features iridescent oxide layers on its surface and possesses four different allotropes.

Nitrous oxide ($N_2O$)

A colourless, relatively unreactive gas where nitrogen has an oxidation state of $+1$.

Nitric oxide ($NO$)

A reactive, paramagnetic, colourless gas where nitrogen has an oxidation state of $+2$.

Dinitrogen trioxide ($N_2O_3$)

A blue liquid or solid ($+3$ oxidation state) that dissociates into $NO$ and $NO_2$.

Nitrogen dioxide ($NO_2$)

A brown, paramagnetic, toxic gas ($+4$ oxidation state) that exists in equilibrium with its colourless dimer, $N_2O_4$.

Dinitrogen pentoxide ($N_2O_5$)

A colourless, volatile crystalline solid where nitrogen has an oxidation state of $+5$.

$$P_4O_6$$

An oxide of phosphorus ($+3$ oxidation state) formed by burning phosphorus in a limited supply of oxygen.

$$P_4O_{10}$$

An oxide of phosphorus ($+5$ oxidation state) formed in excess oxygen; acts as a powerful dehydrating agent and reacts with water to form phosphoric acid.

Nitrogen Hypervalency

Nitrogen cannot form pentahalides or expand its octet (non-hypervalent) because it lacks available d-orbitals in its valence shell.

$PF_5$ Structure

A phosphorus pentahalide that adopts a trigonal bipyramidal structure.

Inert Pair Effect

A phenomenon observed in Bismuth where the $+3$ oxidation state is more stable than the $+5$ state, making $BiF_5$ a powerful oxidizing agent.

Borazine ($B_3N_3H_6$)

Known as "inorganic benzene"; structurally similar to benzene but more reactive toward addition reactions due to polar B-N bonds.

Hexagonal Boron Nitride (BN)

A graphite analogue with eclipsed layers; it is an insulator because electrons are localized on Nitrogen.

Cubic Boron Nitride (BN)

A diamond analogue that is extremely hard and chemically resistant.

Borazane ($H_3B ext{-}NH_3$)

The ethane analogue in boron-nitrogen compounds, categorized as an amine-borane adduct.