Key Terms — INC-02 — Notes

Term	Definition
3c-2e bond	Three-centre-two-electron bond: 2 electrons shared across 3 atoms; electron-deficient
Banana bond	Informal name for the 3c-2e bridging B-H-B bond in diborane
Borax	$Na_{2}B_{4}O_{7}$ · $10H_{2}O$ ; sodium tetraborate decahydrate; used in borax bead test
Borax bead test	Test for cations using glassy borax bead that forms coloured metaborates with metal oxides
Boric acid	$H_{3}BO_{3}$ ; monobasic Lewis acid; layered solid; accepts $OH^{-}$ from water
Lewis acid	Electron-pair acceptor; accepts lone pair from a Lewis base; e.g., $AlCl_{3}$ , $BF_{3}$ , $H_{3}BO_{3}$
Bronsted acid	Proton ( $H^{+}$ ) donor; distinct from Lewis acid
Diborane	$B_{2}H_{6}$ ; simplest boron hydride; electron-deficient; features 2 bridging 3c-2e bonds
Haber process	Industrial synthesis of $NH_{3}$ from $N_{2}$ + $3H_{2}$ ; Fe catalyst; 450°C; 200 atm
Ostwald process	Industrial synthesis of $HNO_{3}$ from $NH_{3}$ via NO and $NO_{2}$ ; Pt/Rh catalyst in Step 1
Inert pair effect	Tendency of $ns^{2}$ electron pair to remain non-bonding in heavier p-block elements
Trigonal bipyramidal	Geometry with 5 bonds: 3 equatorial (120° apart) and 2 axial (90° to equatorial)
$sp^{3}$ d hybridization	Hybridization using s, p, p, p, and d orbitals; gives trigonal bipyramidal geometry
Neutral oxide	Oxide that does not react with water to give acid or base; e.g., $N_{2}$ O, NO
Acidic oxide	Oxide that reacts with water to give an acid or with a base to give a salt; e.g., $N_{2}$$O_{3}$ , $NO_{2}$ , $N_{2}$$O_{5}$
Anhydride	A compound that combines with water to give an acid; e.g., $N_{2}$$O_{5}$ is anhydride of $HNO_{3}$
Paramagnetic	Having unpaired electrons; attracted to magnetic field; e.g., NO, $NO_{2}$
Diamagnetic	Having all paired electrons; weakly repelled by magnetic field
P-OH bond	Bond between phosphorus, oxygen, and hydrogen; determines basicity of P oxoacid
P-H bond	Bond between phosphorus and hydrogen directly; non-ionizable; does not contribute to basicity
Basicity (oxoacid)	Number of ionizable H atoms per molecule; equals number of P-OH bonds in P oxoacids
Allotrope	Different structural forms of the same element; e.g., white, red, black phosphorus
White phosphorus	$P_{4}$ tetrahedra; least stable, toxic, phosphorescent, stored under water
Silicone	Synthetic polymer with repeating ( $R_{2}SiO$ ) unit; water-repellent, heat-stable
Zeolite	Hydrated aluminosilicate with porous structure; used as molecular sieve and ion-exchange catalyst