From diamonds with a hardness that defines the scale to the softness of graphite, from the organic molecules that form our very being to the vast reserves locked in the Earth's crust, carbon's staggering duality is rooted in the profound story told by its atomic properties.
Key Takeaways
- Carbon has an atomic number of 6.
- The standard atomic weight of carbon is 12.011 (relative atomic mass).
- Carbon's electron configuration is [He] 2s2 2p2.
- Diamond (carbon allotrope) has a refractive index of 2.417.
- Graphite consists of layers of sp2 hybridized carbon atoms in hexagonal rings.
- Fullerenes like C60 have a truncated icosahedron structure with 60 carbon atoms.
- Carbon's abundance in the Earth's crust is 200 mg/kg (0.02%).
- Carbon comprises 18.5% of the Earth's crust by mass.
- In the human body, carbon makes up 18% by mass (as organic compounds).
- Carbon-12 is 98.93% of natural carbon.
- Carbon-13 has natural abundance of 1.07%.
- Carbon-14 has a half-life of 5730 years.
- Carbon forms over 10 million known organic compounds.
- DNA contains deoxyribose (C5H10O4) and bases with carbon backbones.
- Proteins are polymers of amino acids with peptide C-N bonds.
Carbon forms diverse allotropes and countless essential organic compounds.
Allotropes
- Diamond (carbon allotrope) has a refractive index of 2.417.
- Graphite consists of layers of sp2 hybridized carbon atoms in hexagonal rings.
- Fullerenes like C60 have a truncated icosahedron structure with 60 carbon atoms.
- Graphene is a single layer of graphite with a thickness of 0.335 nm.
- Carbon nanotubes can be single-walled (SWCNT) with diameters of 0.4-2.5 nm.
- Amorphous carbon lacks long-range order and has 20-50% sp3 content.
- Lonsdaleite (hexagonal diamond) has a density of 3.51 g/cm³.
- Glassy carbon has a density of 1.4-1.6 g/cm³ and is impermeable to gases.
- Nanobuds combine fullerenes and nanotubes, with C60 attached to SWCNT sidewalls.
- Graphite intercalation compounds expand graphite layers by 10-20%.
- Diamond has sp3 hybridization with bond length 154 pm.
- Graphite's interlayer distance is 335 pm.
- C70 fullerene has an elliptical shape with 70 carbon atoms.
- Carbon nanofoam has a density of 0.01 g/cm³.
- Aerographite has a density of 0.18 mg/cm³, lightest known solid.
- Graphene's tensile strength is 130 GPa.
- SWCNTs exhibit ballistic conduction over microns at room temperature.
- Diamond's fluorescence is due to nitrogen-vacancy centers.
- Graphite's lubricity arises from weak van der Waals forces between layers.
- Fullerenes are soluble in organic solvents up to 50 mg/mL for C60.
- Graphene oxide has oxygen content of 30-40 wt%.
- Carbon black has particle sizes of 10-500 nm.
- Activated carbon has surface area up to 3000 m²/g.
- Buckyballs (C60) superconduct at 40 K when doped with alkali metals.
- Diamond anvil cells use diamond to achieve pressures up to 500 GPa.
- Graphite's cleavage is perfect basal {0001}.
Allotropes Interpretation
From diamond’s perfect clarity to graphite’s slippery layers and graphene’s atomic-scale might, carbon proves it’s not just life’s backbone but also nature’s most versatile overachiever.
Biological Importance
- Carbon forms over 10 million known organic compounds.
- DNA contains deoxyribose (C5H10O4) and bases with carbon backbones.
- Proteins are polymers of amino acids with peptide C-N bonds.
- Lipids like fats have long hydrocarbon chains (e.g., palmitic acid C16).
- Carbohydrates are polyhydroxy aldehydes/ketones (e.g., glucose C6H12O6).
- Photosynthesis fixes 120 GtC/year globally.
- Rubisco enzyme fixes CO2 into 3-PGA in Calvin cycle.
- Human diet derives 99% calories from C-containing organics.
- Cellulose (C6H10O5)n is most abundant organic polymer (100 Gt/year).
- Heme in hemoglobin has porphyrin ring with 20 carbons.
- ATP (C10H16N5O13P3) stores cellular energy.
- Cholesterol (C27H46O) is key membrane component.
- Keratin has high cysteine content forming disulfide bonds.
- Carbon dioxide is substrate for C3, C4, CAM photosynthesis paths.
- Glycogen (C24H42O21)n stores glucose in animals.
- Lignin in wood has complex aromatic structure (20-35% dry mass).
- Urea cycle excretes nitrogen as urea (CH4N2O).
- Fatty acid synthesis builds chains from acetyl-CoA (C2 unit).
- Krebs cycle oxidizes acetyl-CoA producing 2 CO2 per turn.
- Nucleic acids have ribose/deoxyribose sugar rings.
- Insulin has 51 amino acids, 6 cysteines forming bonds.
- Melanin pigments protect via polyphenolic carbons.
Biological Importance Interpretation
Life, as we know it, is carbon's grand, persistent project—from the DNA that designs us and the forests that breathe for us to the very calories and crises that animate our existence.
Fundamental Properties
- Carbon has an atomic number of 6.
- The standard atomic weight of carbon is 12.011 (relative atomic mass).
- Carbon's electron configuration is [He] 2s2 2p2.
- The first ionization energy of carbon is 1085.7 kJ/mol.
- Carbon has a covalent radius of 77 pm.
- The van der Waals radius of carbon is 170 pm.
- Carbon's electronegativity on the Pauling scale is 2.55.
- The oxidation states of carbon range from -4 to +4.
- Carbon's atomic radius is 70 pm (calculated).
- The melting point of carbon (sublimes) is approximately 3915 K at standard pressure.
- Carbon's boiling point is around 4827 K.
- The density of amorphous carbon is 1.8-2.1 g/cm³.
- Carbon exhibits catenation, forming long chains of atoms.
- Carbon has 4 valence electrons.
- The thermal conductivity of diamond (carbon allotrope) is 2200 W/(m·K).
- Carbon's Mohs hardness for diamond is 10.
- The speed of sound in diamond is 12,000 m/s.
- Carbon forms tetravalent bonds predominantly.
- The heat of vaporization of carbon is 710.2 kJ/mol.
- Carbon's specific heat capacity is 0.709 J/(g·K).
- The electrical resistivity of graphite is 11-15 μΩ·m.
- Carbon's magnetic ordering is diamagnetic.
- The crystal structure of diamond is face-centered cubic.
- Carbon's liquid range is from 4800 K to 5000 K under pressure.
- The band gap of diamond is 5.5 eV.
- Carbon's thermal expansion coefficient for graphite is 0.6-4.3 x 10^-6 /K.
- The Young's modulus of diamond is 1050-1210 GPa.
- Carbon's Poisson's ratio for diamond is 0.1.
- The bulk modulus of diamond is 440 GPa.
- Carbon's shear modulus for diamond is 478 GPa.
Fundamental Properties Interpretation
Carbon, with its modest atomic number of 6, is the universe's overachieving socialite, humble enough to form the soft lead in a pencil yet audacious enough to forge the hardest diamond, all while being the obliging chemical backbone of life itself due to its perfectly promiscuous four valence electrons.
Industrial Uses
- Carbon black used in tire treads improves wear resistance by 20-30%.
- Activated carbon adsorbs 1000-3000 m²/g for water purification.
- Graphite electrodes in steelmaking consume 400 kg/tonne steel.
- Diamond drill bits cut rock at 10-20 m/hour.
- Carbon fiber composites have strength-to-weight 5x steel.
- CO2 used in enhanced oil recovery extracts 10-20% more oil.
- Carbon nanotubes in batteries increase capacity 10x.
- Graphene in electronics enables transistors at 1 nm scale.
- Coke from coal (90% C) reduces iron ore in blast furnaces.
- Dry ice (solid CO2) sublimes at -78.5°C for cooling.
- Carbon disulfide (CS2) solvent production 1 million tonnes/year.
- SiC (silicon carbide) abrasives from carbon + silica at 2000°C.
- Fullerenes used in lubricants reduce friction by 50%.
- Carbon anodes in aluminum smelting corrode at 50 kg/tonne Al.
- Biochar sequesters carbon in soil, retaining 50% biomass C.
- Carbon capture CCS stores 40 GtCO2 capacity globally.
- Graphite in Li-ion batteries as anode holds 372 mAh/g.
- CVD diamond films for heat sinks dissipate 1000 W/cm².
- Carbon felt filters hot gases up to 3000°C.
- Methanol (CH3OH) from syngas (CO + H2) produces 100 Mt/year.
- Coal gasification yields syngas with 40-60% CO.
- Carbonitriding hardens steel to 1000 HV.
- Lampblack (carbon soot) pigments since 3000 BC.
- UHP graphite electrodes for EAF steelmaking 75 MMT/year demand.
- PEFCs use carbon supports for Pt catalysts.
Industrial Uses Interpretation
From tire treads to steel furnaces, carbon's chameleon-like versatility spans the brutal physics of industry and the subtle promise of future tech, proving it is as indispensable for building our world as it is for dreaming up the next one.
Isotopes
- Carbon-12 is 98.93% of natural carbon.
- Carbon-13 has natural abundance of 1.07%.
- Carbon-14 has a half-life of 5730 years.
- Stable isotopes of carbon are C-12 and C-13.
- Carbon-11 decays by positron emission with half-life 20.3402 min.
- Carbon-14 is produced at 2 atoms/cm²/s in atmosphere.
- δ13C notation measures C-13/C-12 ratio vs. VPDB standard.
- Radiocarbon dating range is up to 50,000 years.
- Carbon-12/u is the basis for atomic mass unit (1/12 mass).
- Heavier carbon isotopes like C-15 have half-life 2.45 s.
- Carbon-14/c ratio in living organisms is 1.2 x 10^-12.
- Suess effect: δ13C decreased 2‰ due to fossil fuel burning.
- Carbon-13 NMR spectroscopy uses 1.07% natural abundance.
- Artificial C-14 production for tracers is via N-14(p,n)C-14.
- Carbon-10 half-life is 19.288 s, decays to B-10.
- Reservoir effect in archaeology adjusts C-14 ages by 400 years for marine samples.
- Carbon-13 enrichment in photosynthesis (C3 vs C4 plants: -27‰ vs -13‰).
- IntCal20 calibration curve for C-14 dating spans 55,000 years.
- Carbon-9 half-life 126 ms, decays by proton emission.
- SHIB variation in tree rings shows solar activity via C-14.
- Carbon-16 half-life 0.74 s, used in nuclear astrophysics.
- Fractionation factor α for C-13 in CO2 is 1.011.
- Carbon-14 specific activity in modern carbon is 0.226 Bq/kg.
Isotopes Interpretation
Carbon, in its myriad isotopic forms, tells the story of everything from the explosive brevity of a dying star to the slow sigh of an ancient tree, proving that the universe keeps its receipts in atomic detail.
Natural Abundance
- Carbon's abundance in the Earth's crust is 200 mg/kg (0.02%).
- Carbon comprises 18.5% of the Earth's crust by mass.
- In the human body, carbon makes up 18% by mass (as organic compounds).
- The atmosphere contains 0.0407% carbon dioxide by volume (415 ppm CO2).
- Oceans hold 38,000 gigatons of carbon, mostly as dissolved bicarbonate.
- Terrestrial biomass contains about 550-600 GtC.
- Coal reserves worldwide are estimated at 1.08 trillion tonnes.
- Natural gas contains methane (CH4), with global reserves of 188 trillion m³.
- Petroleum has about 85% carbon by mass.
- Carbonate rocks like limestone hold 60 million GtC.
- The mantle contains carbon at 100-1000 ppm.
- Meteorites have 0.2-2% carbon.
- Universe abundance of carbon is 0.48% by mass (3rd most abundant after H, He).
- Sun's photosphere has carbon abundance of 310 ppm by mass.
- Seawater has dissolved inorganic carbon at 2.3 mmol/kg.
- Soil organic carbon global stock is 1500-2400 GtC in top 1m.
- Peatlands store 500-600 GtC globally.
- Forests hold 45% of terrestrial biomass carbon (359 GtC).
- Permafrost contains 1300-1600 GtC.
- Global fossil fuel emissions release 10 GtC/year.
- Volcanic outgassing emits 0.1 GtC/year.
- Rivers transport 1 GtC/year to oceans.
- Carbonate weathering sequesters 0.3 GtC/year.
- Black shales contain up to 30% organic carbon.
- Coal is 60-90% carbon by mass.
- Earth's core has negligible carbon (<0.1%).
- Moon's regolith has 100 ppm carbon.
- Mars atmosphere has 95.3% CO2 (carbon source).
Natural Abundance Interpretation
We are a speck of stardust, a thin film of life, built upon a staggering planetary archive of carbon that we are now hastily and carelessly returning to the sky.
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