p-Block Elements & Compounds (Groups 13-15) – Comprehensive Bullet-Point Study Notes

Group 13 (IIIA) Elements – B, Al, Ga, In, Tl

Electronic configurations
- $\text{B}: [He]2s^22p^1$
- $\text{Al}: [Ne]3s^23p^1$
- $\text{Ga}: [Ar]3d^{10}4s^24p^1$
- $\text{In}: [Kr]4d^{10}5s^25p^1$
- $\text{Tl}: [Xe]4f^{14}5d^{10}6s^26p^1$
Common oxidation state: $+3$ (Al, Ga, In, Tl show increasing stability of $+1$ due to inert-pair effect; B never forms $\text{B}^{3+}$ ).
Bonding trend: High IE makes anhydrous halides/oxides essentially covalent.
Metallic character: B (non-metal) → Al (metal) → Ga/In (weakly metallic) → Tl (more metallic).
Abundance (ppm in crust): $\text{Al }\approx 8.3\times10^4>\text{Ga }19>\text{B }9>\text{Tl }0.5>\text{In }0.24$ .

Boron – Occurrence, Extraction & Forms

Occurs mainly as borax $\mathrm{Na2B4O7\cdot10H2O}$ and kernite $\mathrm{Na2B4O7\cdot4H2O}$ .
Amorphous B: Prepared via sequence
1. $\mathrm{Na2B4O7\xrightarrow{HCl} H3BO_3}$
2. $2\mathrm{H3BO3}\xrightarrow{\Delta} \mathrm{B2O3}$
3. $\mathrm{B2O3+3Mg\;\xrightarrow{high\;T}\;2B+3MgO}$
Crystalline B: Thermal decomposition of boron triiodide on tantalum filament:
$2\mathrm{BI3}\rightarrow 2\mathrm{B}+3\mathrm{I2}$
Key properties:
- Amorphous B highly reactive; crystalline B inert.
- Combines with $\mathrm{O2},\,S,\,N2,\,X_2,\,\text{fused} \;\mathrm{NaOH}$ , forms borides with metals (except group I).
- Neutron absorber → control rods in nuclear reactors; strengthens high-impact steels.

Representative Reactions of Amorphous Boron

$4\mathrm{B}+3\mathrm{O2}\xrightarrow{\Delta}2\mathrm{B2O_3}$
$2\mathrm{B}+3\mathrm{Cl2}\rightarrow 2\mathrm{BCl3}$ (analogous for $\mathrm{F2,Br2,I_2}$ )
$2\mathrm{B}+6\mathrm{NaOH}{(\text{fused})}\rightarrow2\mathrm{Na3BO3}+3\mathrm{H2}$
$2\mathrm{B}+3\mathrm{H2O}\xrightarrow{red\;heat}\mathrm{B2O3}+3\mathrm{H2}$

Aluminium – Reactivity & Uses

Passive behaviour: $\sim10^{-4}\text{–}10^{-6}\,\mathrm{mm}$ oxide film prevents attack by $\mathrm{H_2O}$ and air.
Anodising: Electrolytic thickening of oxide layer in dilute $\mathrm{H2SO4}$ → decorative + pigment uptake.
Representative reactions
- $2\mathrm{Al}+6\mathrm{HCl}\rightarrow2\mathrm{Al^{3+}}+6\mathrm{Cl^-}+3\mathrm{H_2}$
- $2\mathrm{Al}+2\mathrm{NaOH}+6\mathrm{H2O}\rightarrow2\mathrm{Na[Al(OH)4]}+3\mathrm{H_2}$ (amphoteric behaviour).
Key applications
1. Structural metal (aircraft, heat exchangers, vehicles)
2. Construction (doors, panels, foils)
3. Containers & cooking ware
4. Weight-efficient power cables (conductivity $\approx2\times$ Cu by mass)
5. Powder (“aluminium bronze”) for metallic paints

Boron & Aluminium Compounds

Boric Acid $\mathbf{H3BO3}$ (Orthoboric Acid)

Preparation: $\mathrm{Na2B4O7+H2SO4+5H2O\rightarrow Na2SO4+4H3BO3}$ .
Acidic behaviour: Weak Lewis acid (accepts $\mathrm{OH^-}$ ), not protonic.
$\mathrm{B(OH)3+2H2O\rightleftharpoons[\,B(OH)4^-]+H3O^+}$
Thermal decomposition:
$2\mathrm{B(OH)3}\xrightarrow{375\,K}\mathrm{2BO(OH)2}+\mathrm{H2O}$ (metaboric) $\mathrm{2BO(OH)2}\xrightarrow{red\,heat}\mathrm{B2O3}+\mathrm{H_2O}$
Structure: $\mathrm{BO_3}$ units in planar sheets linked by H-bonds → flaky crystals.
Uses: Antiseptic eye-wash, food preservative, enamels, pottery glaze, borosilicate glass.

Borax $\mathrm{Na2B4O7\cdot10H2O}$

Natural tincal; also from colemanite $\mathrm{Ca2B6O{11}}$ via $\mathrm{Na2CO_3}$ .
Uses: Alkaline buffer (dyeing/bleaching), preservative, optical & Pyrex glass, flux, ceramic glazes.

Diborane $\mathbf{B2H6}$ – Key Hydride

Syntheses
1. $4\mathrm{BCl3}+3\mathrm{LiAlH4}\rightarrow2\mathrm{B2H6}+3\mathrm{AlCl_3}+3\mathrm{LiCl}$
2. $8\mathrm{BF3}+6\mathrm{LiH}\rightarrow\mathrm{B2H6}+6\mathrm{LiBF4}$
Properties: Toxic, foul-smelling gas; highly exothermic combustion $\Delta H=-1976\,\mathrm{kJ\,mol^{-1}}$ ; hydrolyses to boric acid.
Structure: Four terminal $\mathrm{B–H}$ 2-centre bonds + two $\underline{3c–2e}$ $\mathrm{B!–!H!–!B}$ bridges (banana bonds). Geometry: all B/H_t terminal in one plane, bridging H above–below.

Boron Trifluoride $\mathbf{BF_3}$

Prep: $\mathrm{B2O3+6HF\rightarrow2BF3+3H2O}$ .
Lewis acidity: $\mathrm{BF3+NH3\rightarrow F3B\leftarrow NH3}$ ; similar adduct with ether.
Hydrolysis: $4\mathrm{BF3}+3\mathrm{H2O}\rightarrow\mathrm{H3BO3}+3\mathrm{HBF_4}$ .
Structure: Planar $sp^2$ , $\angle FBF=120^\circ$ ; $\pi$ -back-donation gives partial $\mathrm{B!{=}F}$ multiple-bond character (resonance).
Uses: Friedel–Crafts catalyst (alkylation/acylation), polymerisations.

Aluminium Trichloride $\mathbf{Al2Cl6}$

Preparation: Pass $\mathrm{HCl}$ or $\mathrm{Cl2}$ over hot Al (anhydrous). $2\mathrm{Al}+6\mathrm{HCl}\rightarrow\mathrm{Al2Cl6}+3\mathrm{H2}$
Structure: In solid/liquid – dimer with two Cl bridges; each Al $sp^3$ tetrah. In vapour at $>!!\,700\,K$ dissociates to $\mathrm{AlCl_3}$ monomers.
Hydrolysis: $\mathrm{Al2Cl6+6H2O\rightarrow2[Al(H2O)_6]^{3+}+6Cl^-}$
Use: Classic Lewis-acid Friedel–Crafts catalyst.

Double Salts – Alums

General formula $\mathrm{N^+M^{3+}(SO4)2\cdot12H2O}$ where $\mathrm{N^+ = K^+,NH4^+}$ etc.; $\mathrm{M^{3+}=Al^{3+},Cr^{3+},Fe^{3+}}$ etc.
Potash alum $\mathrm{KAl(SO4)2\cdot12H_2O}$ : mordant in dyeing; water purification (flocculant).

Group 14 (IVA) Elements – C, Si, Ge, Sn, Pb

Valency 4; giant IE prohibits $M^{4+}$ ionic state → covalent compounds dominate.
Inert-pair effect: Stability of $+2$ increases Ge→Sn→Pb.
Metallic character: C, Si non-metal, Ge metalloid, Sn/Pb metals.

Catenation & Bond Strength

$E–E$ bond energies: $\mathrm{C–C}$ (348 kJ mol⁻¹) ≫ $\mathrm{Si–Si}$ (226 kJ mol⁻¹) → extensive chains/rings only for carbon.

Allotropes of Carbon

Diamond
- 3-D $sp^3$ tetrahedral network; $d_{C–C}=154\,\text{pm}$ .
- Hardest natural substance; electrical insulator; burns $>800^\circ!C$ → $\mathrm{CO_2}$ .
- Fluorination at $973\,K$ → $\mathrm{CF_4}$ .
- Uses: cutting/grinding tools, dies, jewellery.
Graphite
- Layers of $sp^2$ hexagonal sheets; delocalised $\pi$ electrons → electrical conductor; inter-layer vdW $\approx340\,\text{pm}$ .
- Chemically more reactive than diamond; burns at $873\,K$ ; converts to $\mathrm{graphite\;bisulfate}$ in conc. $\mathrm{H2SO4}$ .
- Uses: electrodes, lubricants, crucibles, ‘lead’ pencils, heat-resistant paints.
Fullerenes (e.g. $\mathrm{C_{60}}$ soccer-ball) – hollow molecular cages; surface functionalisation yields novel materials.

Oxides of C & Si

CO (neutral): $\mathrm{C+\tfrac12O2}\rightarrow\mathrm{CO}$ ; colourless poisonous gas; strong reducing agent (blast furnace, Ni carbonyl $\mathrm{Ni(CO)4}$ , methanol synthesis $\mathrm{CO+2H_2}$ ).
CO₂ (acidic): Linear $\mathrm{O=C=O}$ , dry-ice sublimes $-78^\circ!C$ ; uses refrigerant, carbonation, soda manufacture.
SiO₂ (acidic): Network solid (quartz, cristobalite); reacts only with bases or $\mathrm{F2/HF}$ $\Rightarrow\mathrm{SiF4}$ .

Tetrachlorides – $\mathrm{CCl4}$ vs $\mathrm{SiCl4}$

Both $sp^3$ , tetrahedral.
Hydrolysis: $\mathrm{CCl4}$ inert (no d-orbitals); $\mathrm{SiCl4}$ + $4\mathrm{H2O}\rightarrow\mathrm{Si(OH)4}+4\mathrm{HCl}$ via $d\pi–p\sigma$ attack.
Silicon forms complex $\mathrm{[SiF_6]^{2-}}$ (empty 3d), carbon cannot.

Silicon Carbide (Carborundum) $\mathbf{SiC}$

Made $\mathrm{SiO_2+3C\xrightarrow{electric\,furnace}SiC+2CO}$ .
Diamond-like tetrahedral giant lattice → extreme hardness; industrial abrasive.

Silicones – $\mathrm{[\,R2SiO\,]n}$ Polymers

Prepared by hydrolysis/condensation of mixed $\mathrm{RnSiCl{4-n}}$ (Cu-catalysed direct process $\mathrm{RCl+Si}$ → chlorosilane).
Control of $R$ groups & chain-stoppers ( $\mathrm{R_3SiCl}$ ) tunes viscosity (oils), elasticity (rubbers), resins.
Properties: thermal stability, water-repellency, low T-dependence of viscosity.

Silicates & Zeolites

Built from $\mathrm{SiO_4^{4-}}$ tetrahedra sharing 0–4 O atoms.
- $\mathrm{SiO4^{4-}}$ (orthosilicate), $\mathrm{Si2O7^{6-}}$ (pyro-), $\mathrm{(SiO3){n}^{2n-}}$ chains, rings $\mathrm{Si3O9^{6-}}$ , sheets $\mathrm{Si4O_{10}^{4-}}$ (mica, clay).
Zeolites: 3-D aluminosilicate frameworks with channels; ion-exchange (water softening by Na⁺/Ca²⁺ swap), molecular sieves (size-selective adsorption, hydrocarbon separations).

Group 15 (VA) Elements – N, P, As, Sb, Bi

Complete octet via $-3$ (only N significant), form covalent $+3,+5$ compounds. Inert-pair effect stabilises $+3$ for Sb/Bi.
Multiple bonding (N≡N), $\pi$ -bonding absent for heavier congeners.

Nitrogen – Occurrence & Isolation

78 % of air by volume.
Laboratory: Thermal $\mathrm{NH4NO2\rightarrow N2+2H2O}$ ; oxidation of excess NH₃ by Cl₂ (avoid $\mathrm{NCl_3}$ ).
Industrial: Fractional distillation of liquid air (bp $N2=-195.8^\circ!C$ vs $O2=-183^\circ!C$ ).

Properties

Colourless, odourless, non-toxic diluent; inert due to triple bond energy.
Reactivity emerges at high T/pressure/catalyst.
- $\mathrm{N2+3H2\rightleftharpoons 2NH_3}$ (Haber, $200\,\text{atm}, 723\,K, Fe/Mo$ )
- Lightning: $\mathrm{N2+O2\rightarrow 2NO}$ .
Uses: Ammonia, nitric acid, fertilisers, inert atmosphere, light-bulb fill, cryogenic liquid.

Oxides of Nitrogen – Structures

$\mathrm{N2O, NO, N2O3, NO2\;(N2O4), N2O5}$ ; diverse $\pi$ -bonding patterns (see structural sketches in transcript).

Ammonia $\mathbf{NH_3}$

Prep: Heating ammonium salt + base $\rightarrow$ NH₃; hydrolysis of nitrides; industrial Haber.
Physical: Pungent gas; liquefies at 9 atm (298 K); extensive H-bonding in $\mathrm{NH_3(l)}$ ; highly soluble in water.
Aqueous equilibrium: $\mathrm{NH3+H2O\rightleftharpoons NH_4^++OH^-}$ ; “NH₄OH” exists only as ions.
Structure: $sp^3$ trigonal pyramid; $\angle HNH=107^\circ$ (lone-pair repulsion).
Key reactions
- Thermal dissociation $>773\,K$ .
- Combustion: In $\mathrm{O2}$ → $\mathrm{N2/H_2O}$ ; on hot Pt → $\mathrm{NO}$ (basis of Ostwald HNO₃ process).
- Reducing agent for metal oxides $3\mathrm{PbO}+2\mathrm{NH3}\rightarrow3\mathrm{Pb}+N2+3\mathrm{H_2O}$ .
- Forms ammonium salts/acids; complexation with transition metals $[\mathrm{Cu(NH3)4}]^{2+}, [\mathrm{Ag(NH3)2}]^+$ etc.
Uses: Fertiliser $\mathrm{(NH4)2SO_4}$ , nitric-acid feedstock, Solvay soda, refrigeration (liquid NH₃), household cleaner.

Nitric Acid $\mathbf{HNO_3}$

Lab prep: $\mathrm{NaNO3+H2SO4\xrightarrow{\Delta} HNO3+NaHSO_4}$ .
Ostwald process:
1. $4\mathrm{NH3}+5\mathrm{O2}\xrightarrow{\mathrm{Pt},1173K}4\mathrm{NO}+6\mathrm{H_2O}$
2. $2\mathrm{NO}+O2\rightarrow2\mathrm{NO2}$
3. $3\mathrm{NO2}+H2O\rightarrow2\mathrm{HNO_3}+NO$ (re-circulated)
Properties: $\mathrm{pK_a}\approx -1.4$ (strong acid); $98\%$ azeotrope bp $393\,K$ ; oxidising agent.
Oxidation examples
- $\mathrm{Cu+4HNO3(conc.)\rightarrow Cu(NO3)2+2NO2+2H_2O}$
- $\mathrm{I2+10HNO3\rightarrow 2HIO3+10NO2+4H_2O}$
Organic nitrations: $\mathrm{C3H5(OH)3+3HNO3\xrightarrow{conc.H2SO4} C3H5(NO2)3}$ (nitroglycerine).
Structure: Planar $sp^2$ , two $\mathrm{N{-}O}$ equal (resonance), one $\mathrm{N=O}$ , $\angle\approx102^\circ$ .
Uses: Fertiliser nitrates, explosives (TNT, NG), oxidiser (rocket grade 100 % HNO₃), laboratory oxidant, aqua regia component.

Phosphorus – Allotropy & Compounds

Allotropes
1. White (P₄) – tetrahedral molecules, strained $60^\circ$ $\angle$ ; soft, waxy, reactive, stored under water.
2. Red – polymeric; formed by heating white $\approx270^\circ!C$ in absence of air; more stable, granular, non-poisonous.
3. Black – flaky, metallic-looking; obtained at high pressure + $200^\circ!C$ ; conductor similar to graphite.

Phosphorus Halides

PCl₃: $\mathrm{P4+6Cl2\rightarrow4PCl3}$ ; colourless fuming liquid; hydrolysis → $\mathrm{H3PO_3+HCl}$ ; converts ROH/RCOOH → RCl/acid chlorides.
PCl₅: $\mathrm{PCl3+Cl2\rightleftharpoons PCl5}$ (ice-cold); trigonal-bipyramid vapour, ionic solid $[\mathrm{PCl4^+}][\mathrm{PCl6^-}]$ ; hydrolysis yields $\mathrm{POCl3}$ then $\mathrm{H3PO4}$ .

Oxyacids of Phosphorus – Summary Table

Acid	Formula	Basicity	Key notes
Hypophosphorous	$\mathrm{H<em>3PO</em>2}$ (or $\mathrm{H_2P(O)OH}$ )	1	Strong reducing agent $\to\ H<em>3PO</em>4$
Phosphorous	$\mathrm{H<em>3PO</em>3}$	2	Mild reducing; from $\mathrm{PCl<em>3+H</em>2O}$
Orthophosphoric	$\mathrm{H<em>3PO</em>4}$	3	Fertiliser super-phosphate; forms $\mathrm{PO_4^{3-}}$
Pyrophosphoric	$\mathrm{H<em>4P</em>2O_7}$	4	Produced by $\mathrm{2H<em>3PO</em>4\xrightarrow{\Delta}H<em>4P</em>2O<em>7+H</em>2O}$
Metaphosphoric	$\mathrm{(HPO<em>3)</em>n}$	n	Ring/linear polymers

Pyrophosphoric structure: $\mathrm{HO{-}P(=O)(OH){-}O{-}P(=O)(OH){-}OH}$ .

Comparative Hydrolytic Behaviour

$\mathrm{CCl_4}$ : inert (no empty d-orbital).
$\mathrm{SiCl_4}$ : rapid hydrolysis via $\mathrm{O\to Si}$ donation into 3d orbital.

Ethical / Practical Implications

Boron neutron absorption: crucial for safe nuclear reactor control.
CO toxicity: public health importance (exhaust ventilation, detector usage).
NH₃ / fertilisers: Green-revolution food security vs environmental eutrophication; need for sustainable N-fixation.
Nitrates & explosives: Regulatory handling to prevent misuse.
Zeolites: cleaner catalysis & water softening (reduces detergent phosphate pollution).

Key Numerical / Statistical Data

$\text{IE}_1(\text{Al})=578\,\mathrm{kJ\,mol^{-1}}$ ; $m.p.(\text{Al})=660^\circ!C$ .
$\text{B–H}_{\text{bridge}}$ length in $\mathrm{B2H6}$ : $1.19\,\text{Å}$ ; terminal $\mathrm{B–H}=1.20\,\text{Å}$ .
$\angle\mathrm{H!–!B!–!H}_{\text{bridge}}\approx97^\circ$ .
$\mathrm{N_2}$ liquefaction bp $-195.8^\circ!C$ ; oxygen bp $-183^\circ!C$ (basis for distillative separation).
Haber optimum: $\sim200\,\text{atm},\,673\text{–}773\,K,\,\text{Fe/Mo}$ catalyst, $10\%$ conversion per pass.

Connections & Cross-Links

Diagonal relationship: Boron ↔ Silicon (covalent network tendency, acidic oxides).
Inert-pair effect parallels between group 13 and 14 heavier elements (Tl⁺, Pb²⁺).
Lewis acidity series: $\mathrm{BF3>AlCl3>PCl_5}$ – exploited in organic synthesis.
Hydrogen bonding motifs: $\mathrm{B(OH)_3}$ sheets vs ice vs layered silicates.

Exam Tips

Always depict $\underline{3c–2e}$ bonds in diborane; mention electron deficiency.
Emphasise why $\mathrm{BF_3}$ is acidic (sextet) yet $\mathrm{B–F}$ back-bonding shortens bond.
Contrast catenation energies when asked about C vs Si chemistry.
For alum formulae quote $\mathrm{M^+M^{3+}(SO4)2\cdot12H_2O}$ and show ion tests.
Remember passivation of Al in conc. $\mathrm{HNO_3}$ (protective oxide).

p-Block Elements & Compounds (Groups 13-15) – Comprehensive Bullet-Point Study Notes

Group 13 (IIIA) Elements – B, Al, Ga, In, Tl

Boron – Occurrence, Extraction & Forms

Representative Reactions of Amorphous Boron

Aluminium – Reactivity & Uses

Boron & Aluminium Compounds

Boric Acid $\mathbf{H<em>3BO</em>3}$ (Orthoboric Acid)

Borax $\mathrm{Na<em>2B</em>4O<em>7\cdot10H</em>2O}$

Diborane $\mathbf{B<em>2H</em>6}$ – Key Hydride

Boron Trifluoride $\mathbf{BF_3}$

Aluminium Trichloride $\mathbf{Al<em>2Cl</em>6}$

Double Salts – Alums

Group 14 (IVA) Elements – C, Si, Ge, Sn, Pb

Catenation & Bond Strength

Allotropes of Carbon

Oxides of C & Si

Tetrachlorides – $\mathrm{CCl<em>4}$ vs $\mathrm{SiCl</em>4}$

Silicon Carbide (Carborundum) $\mathbf{SiC}$

Silicones – $\mathrm{[\,R<em>2SiO\,]</em>n}$ Polymers

Silicates & Zeolites

Group 15 (VA) Elements – N, P, As, Sb, Bi

Nitrogen – Occurrence & Isolation

Properties

Oxides of Nitrogen – Structures

Ammonia $\mathbf{NH_3}$

Nitric Acid $\mathbf{HNO_3}$

Phosphorus – Allotropy & Compounds

Phosphorus Halides

Oxyacids of Phosphorus – Summary Table

Comparative Hydrolytic Behaviour

Ethical / Practical Implications

Key Numerical / Statistical Data

Connections & Cross-Links

Exam Tips

p-Block Elements & Compounds (Groups 13-15) – Comprehensive Bullet-Point Study Notes

Group 13 (IIIA) Elements – B, Al, Ga, In, Tl

Boron – Occurrence, Extraction & Forms

Representative Reactions of Amorphous Boron

Aluminium – Reactivity & Uses

Boron & Aluminium Compounds

Boric Acid H<em>3BO</em>3\mathbf{H<em>3BO</em>3}H<em>3BO</em>3 (Orthoboric Acid)

Borax Na<em>2B</em>4O<em>7⋅10H</em>2O\mathrm{Na<em>2B</em>4O<em>7\cdot10H</em>2O}Na<em>2B</em>4O<em>7⋅10H</em>2O

Diborane B<em>2H</em>6\mathbf{B<em>2H</em>6}B<em>2H</em>6 – Key Hydride

Boron Trifluoride BF3\mathbf{BF_3}BF3​

Aluminium Trichloride Al<em>2Cl</em>6\mathbf{Al<em>2Cl</em>6}Al<em>2Cl</em>6

Double Salts – Alums

Group 14 (IVA) Elements – C, Si, Ge, Sn, Pb

Catenation & Bond Strength

Allotropes of Carbon

Oxides of C & Si

Tetrachlorides – CCl<em>4\mathrm{CCl<em>4}CCl<em>4 vs SiCl</em>4\mathrm{SiCl</em>4}SiCl</em>4

Silicon Carbide (Carborundum) SiC\mathbf{SiC}SiC

Silicones – [ R<em>2SiO ]</em>n\mathrm{[\,R<em>2SiO\,]</em>n}[R<em>2SiO]</em>n Polymers

Silicates & Zeolites

Group 15 (VA) Elements – N, P, As, Sb, Bi

Nitrogen – Occurrence & Isolation

Properties

Oxides of Nitrogen – Structures

Ammonia NH3\mathbf{NH_3}NH3​

Nitric Acid HNO3\mathbf{HNO_3}HNO3​

Phosphorus – Allotropy & Compounds

Phosphorus Halides

Oxyacids of Phosphorus – Summary Table

Comparative Hydrolytic Behaviour

Ethical / Practical Implications

Key Numerical / Statistical Data

Connections & Cross-Links

Exam Tips

Boric Acid $\mathbf{H<em>3BO</em>3}$ (Orthoboric Acid)

Borax $\mathrm{Na<em>2B</em>4O<em>7\cdot10H</em>2O}$

Diborane $\mathbf{B<em>2H</em>6}$ – Key Hydride

Boron Trifluoride $\mathbf{BF_3}$

Aluminium Trichloride $\mathbf{Al<em>2Cl</em>6}$

Tetrachlorides – $\mathrm{CCl<em>4}$ vs $\mathrm{SiCl</em>4}$

Silicon Carbide (Carborundum) $\mathbf{SiC}$

Silicones – $\mathrm{[\,R<em>2SiO\,]</em>n}$ Polymers

Ammonia $\mathbf{NH_3}$

Nitric Acid $\mathbf{HNO_3}$