6 C Carbon 12.011
Nonmetal p-block Period 2 Group 14

Carbon

C · Element 6 · Carbon group

The backbone of every known living thing, and the most versatile bonder in the periodic table.

STATE AT 20°C Solid
ATOMIC MASS 12.011 u
ELECTRON CONFIGURATION [He] 2s² 2p²

Structure

The carbon atom

Not a diagram of dots on rings — a Monte-Carlo sample of the actual probability density |ψ|² for each occupied subshell. Drag to rotate. Blue and violet mark opposite signs of the wavefunction, which is what makes bonding possible.

Orbital cloud

Measured values

Property sheet

Every bar shows where carbon sits among all 118 elements for that property.

Physical

Density 2.267 g/cm³ 19%
Sublimation point 3915 Kat 1 atm
Melting point 4600 Kat 10.8 MPa
Specific heat 0.709 J/g·K
Thermal conductivity 0.16 W/m·K 11%

Atomic

Atomic radius 70 pm 5%
Covalent radius 76 pm
Van der Waals radius 170 pm

Electronic

Electronegativity 2.55 90%
Ionisation energy 1086.4 kJ/mol 90%
Electron affinity 121.6 kJ/mol 83%

Occurrence

Abundance in crust 2000 mg/kg 92%

Identity

SymbolC
Atomic number6
Atomic mass12.011 u
CategoryNonmetal
Blockp
Crystal structurediamond cubic
Oxidation states-4, -3, -2, -1, 0, +1, +2, +3, +4
DiscoveredPrehistoric
Discovered byKnown since antiquity

Sources: IUPAC 2021 standard atomic weights · CRC Handbook of Chemistry and Physics · NIST. Values marked ~ are predicted rather than measured.

Size, to scale

How big is a carbon atom?

Radius 70 pm — that is 0.07 nm, so about 7143 million of them side by side would span a millimetre.

Thermal range

Solid, gas — and when

At ordinary pressure carbon has no liquid phase at all. It sublimes at 3915 K, passing straight from solid to vapour. The 4600 K melting point is real, but only above about 10.8 MPa.

Where it sits

Position in the table

Carbon sits in period 2, group 14. Everything in group 14 shares the same outer-electron count, which is why they behave so similarly.

OTHER NONMETALS

All nonmetals

The story

What carbon is, and how we found it

Carbon is a leading shapeshifter of the periodic table and the foundation of all life on Earth. This incredible element can transform into sparkling diamonds (the hardest natural material), slippery graphite (used in pencils), and even exotic fullerenes that look like soccer balls at the molecular level. Every living thing - from the tiniest bacteria to the mightiest redwood tree - is built on a carbon backbone. Your DNA, proteins, fats, and carbohydrates all depend on carbon's unique ability to form four strong bonds, creating endless molecular possibilities. Carbon is also at the center of climate change discussions, as carbon dioxide in our atmosphere acts like a blanket, trapping heat and warming our planet. From prehistoric campfires to modern carbon fiber race cars, this element has shaped human civilization.

The discovery of carbon

Known Since the Dawn of Humanity

Carbon has no single discoverer because humans have used various forms of carbon since prehistoric times. However, understanding carbon as a distinct chemical element required millennia of scientific evolution and represents one of chemistry's most fundamental breakthroughs.

Prehistoric Carbon Mastery (500,000+ years ago)

Early humans discovered carbon's power through fire and charcoal. Archaeological evidence from sites like Qesem Cave in Israel shows controlled fire use 400,000 years ago. Our ancestors learned that burning wood in limited oxygen produced charcoal - nearly pure carbon that burned hotter and longer than wood.

This knowledge revolutionized human civilization:

  • Cooking: Made nutrients more available and food safer
  • Toolmaking: Enabled smelting of metals like copper and bronze
  • Art: Cave paintings using charcoal pigments from 30,000 years ago
  • Medicine: Activated charcoal for treating poisoning

Ancient Carbon Technologies

Steel production (1500 BCE): Hittite metallurgists discovered that adding carbon to iron created steel - a significant alloy that changed warfare and agriculture for very long periods. Chinese inventors perfected cast iron production around 500 BCE, using carbon content to control metal properties.

Diamond knowledge (400 BCE): Ancient Indians discovered diamonds in river gravels and recognized their extraordinary hardness. Sanskrit texts called diamonds "vajra" (thunderbolt), believing they were formed by lightning strikes.

Scientific Recognition (1700s-1800s)

Antoine Lavoisier (1772): The "father of modern chemistry" proved that diamond and charcoal were different forms of the same element. His combustion experiments showed both substances produced identical amounts of carbon dioxide when burned, revolutionizing understanding of chemical elements.

Lavoisier wrote: "We must conclude that diamond is nothing but crystallized carbon." This insight unified seemingly different materials under one element and established the concept of allotropes.

Carl Wilhelm Scheele (1779): Independently discovered that graphite ("black lead") was also pure carbon, not lead as previously believed. His work helped establish carbon as element number 6.

The Modern Carbon Revolution

Friedrich Kekulé (1858): Proposed that carbon atoms could form chains and rings, laying the foundation for organic chemistry. His famous benzene ring structure (allegedly inspired by a dream of a snake biting its tail) explained aromatic compounds.

Jacobus van 't Hoff and Joseph Le Bel (1874): Independently proposed tetrahedral carbon, explaining why carbon compounds could exist in mirror-image forms. This breakthrough launched stereochemistry and explained drug behavior.

20th Century Breakthroughs

Percy Bridgman (1955): First artificial diamond synthesis under extreme pressure, proving diamonds could be manufactured.

Richard Smalley, Robert Curl, and Harold Kroto (1985): Discovered fullerenes (C₆₀), earning the 1996 Nobel Prize and launching nanotechnology.

Andre Geim and Konstantin Novoselov (2004): Isolated graphene using adhesive tape, earning the 2010 Nobel Prize and opening the era of two-dimensional materials.

Carbon's Future

Carbon research continues with discoveries like carbyne (one-dimensional carbon chains) and predictions of even more exotic forms. Each breakthrough reveals new possibilities for this most versatile element.

Applications

What carbon is used for

The Element of Life and Technology

Carbon is the foundation of existence itself - the element that makes life possible and drives technological revolution. From the DNA in our cells to the strongest materials known to science, carbon's unique ability to form complex structures makes it irreplaceable in virtually every aspect of modern civilization.

Significant Carbon Materials

Diamond: a leading benchmark for hardness and thermal conductivity. Industrial applications include:

  • Cutting tools: Diamond-tipped drill bits can cut through any material on Earth
  • Quantum computing: Synthetic diamond hosts nitrogen-vacancy centers for quantum information processing
  • Heat sinks: Electronics cooling in high-performance computers and LED systems
  • Medical devices: Diamond-coated surgical instruments and artificial joints

Graphene: The wonder material - single layer of carbon atoms arranged in a hexagonal lattice:

  • Electronics: Flexible displays, ultra-fast transistors, and quantum computers
  • Energy storage: Supercapacitors and next-generation battery electrodes
  • Water filtration: Membranes that can desalinate seawater while allowing rapid water flow
  • Biomedical: Drug delivery systems and neural interfaces

Carbon Nanotubes: Cylindrical carbon structures stronger than steel but lighter than aluminum:

  • Aerospace: Boeing and Airbus use CNT composites in aircraft components
  • Space elevators: Theoretical megastructure requiring CNT tethers
  • Electronics: Ultra-miniaturized circuits and transparent conductive films
  • Medicine: Targeted cancer therapy and artificial muscles

Steel and Metallurgy

Carbon transforms iron into steel - humanity's most important structural material:

  • Construction: Skyscrapers, bridges, and infrastructure worldwide
  • Automotive: Car bodies, engines, and safety components
  • Tools: Cutting implements, machine components, and precision instruments
  • Specialized alloys: Stainless steel (with chromium), tool steel, and Damascus steel

Carbon Fiber Revolution

Carbon fiber composites combine incredible strength with minimal weight:

  • Aerospace: Boeing 787 Dreamliner is 50% carbon fiber by weight
  • Automotive: Formula 1 cars, luxury supercars, and electric vehicle bodies
  • Sports equipment: Tennis rackets, golf clubs, bicycles, and protective gear
  • Wind energy: Turbine blades spanning over 100 meters

Environmental & Energy Applications

Carbon capture and storage: Fighting climate change through technological innovation:

  • Direct air capture: Machines that extract CO₂ from the atmosphere
  • Industrial sequestration: Capturing emissions from power plants and factories
  • Carbon utilization: Converting captured CO₂ into useful products

Activated carbon: The universal purification material:

  • Water treatment: Municipal water systems and home filtration
  • Air purification: Gas masks, industrial scrubbers, and HVAC systems
  • Medical applications: Poison treatment and kidney dialysis
  • Food industry: Sugar refining and beverage processing

Everyday Carbon Products

  • Writing materials: Pencil graphite, charcoal for art, carbon paper for copies
  • Cooking: Charcoal grills, barbecue briquettes, activated carbon water filters
  • Cleaning products: Activated carbon air fresheners, odor absorbers, aquarium filters
  • Personal care: Charcoal toothpaste, face masks, detox products
  • Textiles: Carbon fiber threads in athletic wear and heated clothing

Transportation & Automotive

  • Steel structures: Car frames, engine blocks, transmission components
  • Carbon fiber: BMW i3 body panels, McLaren supercars, racing components
  • Tires: Carbon black reinforcement in rubber compounds
  • Lubricants: Graphite in locks, hinges, and mechanical systems
  • Brake systems: Carbon-ceramic brake discs in high-performance vehicles

Construction & Architecture

  • Steel frameworks: Skyscrapers like Empire State Building, bridges, tunnels
  • Concrete reinforcement: Rebar in foundations, roads, and infrastructure
  • Insulation: Carbon fiber heating elements in radiant floor systems
  • Windows: Carbon coatings for energy-efficient glass
  • Roofing: Carbon fiber reinforced materials for lightweight, strong structures

Electronics & Technology

  • Computer components: Graphite thermal pads, carbon nanotube transistors
  • Smartphones: Graphene research for flexible displays and fast charging
  • Batteries: Graphite anodes in lithium-ion batteries (Tesla, iPhone)
  • Solar panels: Carbon contacts and conductors
  • Audio equipment: Carbon fiber speaker cones and headphone components

Sports & Recreation

  • Tennis equipment: Wilson, Head, and Babolat carbon fiber rackets
  • Golf clubs: Carbon fiber shafts and clubheads
  • Bicycles: Trek, Specialized, and Cannondale carbon frames
  • Fishing gear: Carbon fiber rods and reels
  • Protective equipment: Helmets, body armor, and safety gear

Agriculture & Environment

  • Soil improvement: Biochar for carbon sequestration and plant growth
  • Water treatment: Activated carbon filters for irrigation systems
  • Greenhouse structures: Carbon fiber frames and components
  • Animal feed: Activated charcoal for livestock health

Where it comes from

Natural occurrence

2000 mg/kg of Earth's crust · more abundant than 92% of elements

Cosmic Abundance - The Fourth Element

Carbon ranks as the fourth most abundant element in the universe by mass, forged in the nuclear furnaces of massive stars through the legendary triple-alpha process. This cosmic abundance makes carbon the foundation for complex chemistry throughout the cosmos.

Stellar Nucleosynthesis

Carbon forms inside giant stars when three helium-4 nuclei (alpha particles) fuse together in a process discovered by Fred Hoyle. This reaction requires temperatures above 100 million Kelvin and was so improbable that Hoyle predicted the existence of a specific carbon-12 energy level to make it possible - a prediction later confirmed and now called the "Hoyle state."

When massive stars explode as supernovae, they scatter carbon throughout the galaxy, seeding space with the raw materials for life. Every carbon atom in your body was forged in a star's core and distributed by stellar death - truly making us "star stuff."

Earth's Carbon Reservoirs

Earth contains approximately 1.85 × 10¹⁸ tons of carbon distributed across multiple reservoirs:

Geological Carbon

  • Sedimentary rocks: 99.9% of Earth's carbon locked in limestone, coal, and organic-rich shales
  • Coal deposits: 1 trillion tons worldwide, formed from ancient forests over 300 million years
  • Oil and gas: Hydrocarbons trapped in underground reservoirs
  • Diamond deposits: Formed deep in Earth's mantle under extreme pressure
  • Graphite ore: Metamorphic deposits in Sri Lanka, Madagascar, and Brazil

Natural Diamond Formation

Diamonds form 150-200 kilometers beneath Earth's surface in the mantle, where pressures exceed 45,000 atmospheres and temperatures reach 1,200°C. Volcanic eruptions called kimberlite pipes bring diamonds to the surface in violent explosions that travel faster than the speed of sound.

Famous diamond locations include:

  • Botswana: Produces 20% of world's diamonds by value
  • Russia: Siberian mines in permafrost conditions
  • Canada: Arctic diamond mines discovered in the 1990s
  • Australia: Argyle mine produced rare pink diamonds

Atmospheric & Oceanic Carbon

The carbon cycle continuously exchanges carbon between atmosphere, oceans, and biosphere:

  • Atmospheric CO₂: 415 ppm, the highest in 3 million years
  • Ocean dissolved carbon: 38,000 billion tons, 50 times more than the atmosphere
  • Marine carbonates: Coral reefs and shell-forming organisms
  • Deep ocean circulation: Transports carbon globally over centuries

Biological Carbon

Living organisms contain about 550 billion tons of carbon:

  • Forests: Amazon rainforest alone stores 150-200 billion tons
  • Soil organic matter: 1,600 billion tons globally
  • Marine life: Phytoplankton and ocean ecosystems
  • Fossil carbon: Ancient organic matter in sediments

Carbon Allotropes in Nature

Carbon exists in multiple forms with dramatically different properties:

  • Diamond: Transparent, hardest natural material
  • Graphite: Soft, conductive, found in metamorphic rocks
  • Fullerenes: Discovered in soot, also found in space
  • Amorphous carbon: Charcoal, soot, and organic residues

Handling

Safety

Generally Safe with Form-Specific Precautions

Pure carbon in its common forms is Low-toxicity and biologically inert, but different carbon allotropes and compounds require specific safety considerations. The primary concerns involve particle inhalation and specialized carbon materials.

Respiratory Considerations

Carbon black and fine particles: Inhalation of carbon particles can cause respiratory irritation. Long-term exposure to carbon black may increase lung cancer risk according to IARC classification (Group 2B - possibly carcinogenic).

OSHA exposure limits:

  • Carbon black: 3.5 mg/m³ (8-hour TWA)
  • Graphite (natural): 2.5 mg/m³ respirable fraction
  • Graphite (synthetic): 15 mg/m³ total dust, 5 mg/m³ respirable

Nanomaterial Safety

Carbon nanotubes: Research suggests potential health risks similar to asbestos due to their fibrous structure. Handle with extreme caution:

  • Use fume hoods and negative pressure environments
  • Wear N95 or higher respiratory protection
  • Avoid dry sweeping - use wet cleaning methods
  • Follow nanotechnology safety protocols

Graphene: Limited toxicity data available. Preliminary studies suggest low acute toxicity but potential for cellular penetration. Use standard nanomaterial safety procedures.

Industrial Safety Measures

  • Ventilation: Local exhaust ventilation for dusty operations
  • Personal protection: Dust masks, safety glasses, protective clothing
  • Housekeeping: Regular cleaning to prevent dust accumulation
  • Training: Worker education on proper handling procedures

Specific Material Hazards

Activated carbon: Generally safe but may adsorb toxic substances from air. Dispose of used carbon as hazardous waste if contaminated.

Diamond tools: No inherent toxicity, but machining can create respirable particles. Use appropriate dust collection systems.

Carbon fiber: Skin and respiratory irritant due to fine filaments. Can conduct electricity - avoid contact with electrical systems.

Fire and Explosion Risks

Dust explosion hazard: Fine carbon powders can form explosive mixtures with air. Minimum ignition energy is very low for some carbon dusts.

Prevention measures:

  • Eliminate ignition sources in dusty areas
  • Use explosion-proof electrical equipment
  • Maintain humidity levels above 45% when possible
  • Install dust collection systems with explosion venting

Consumer Product Safety

Charcoal and barbecue products: Safe for intended use but:

  • Never use charcoal indoors - produces deadly carbon monoxide
  • Allow proper ventilation during outdoor cooking
  • Store in dry areas to prevent spontaneous combustion

Pencil graphite: low-toxicity if ingested in small amounts (despite the name "lead pencil")

Carbon supplements: Activated charcoal can interfere with medications - consult healthcare providers

Quick answers

Carbon: common questions

What is Carbon?

Carbon (symbol C) is element 6 on the periodic table, a nonmetal in period 2, group 14. The backbone of every known living thing, and the most versatile bonder in the periodic table. At room temperature it is a solid.

What is the electron configuration of Carbon?

Carbon's ground-state electron configuration is [He] 2s² 2p², giving 2 occupied shells holding 2, 4 electrons respectively. Its outer shell holds 4 electrons, which is what sets its bonding behaviour.

Does Carbon melt, or does it sublime?

At ordinary pressure carbon does not melt at all — it sublimes, passing straight from solid to vapour at about 3915 K (3641.9 °C). A liquid phase only exists above roughly 10.8 MPa, where it melts near 4600 K. That is why a single "melting point" for carbon is misleading without a stated pressure.

What is the atomic mass of Carbon?

The standard atomic weight of Carbon is 12.011 u. That is a weighted average across its naturally occurring isotopes, which is why it is rarely a whole number.

How dense is Carbon?

Carbon has a density of 2.267 g/cm³. Water is 1.0 g/cm³, so a block of carbon is about 2.3× heavier.

What is the electronegativity of Carbon?

Carbon has a Pauling electronegativity of 2.55. The scale runs from 0.70 (francium, the least greedy for electrons) to 3.98 (fluorine, the most). Values in this middle band tend to form covalent rather than strongly ionic bonds.

Who discovered Carbon, and when?

Carbon has been known since antiquity — it occurs in a form usable without smelting, so no single person can be credited with its discovery. The name comes from latin carbo, "charcoal".

How common is Carbon on Earth?

Carbon makes up about 0.2% of the Earth's crust — common enough to be mined at scale.