Atomic Number 6 - Carbon or C

Get Facts About Element Atomic Number 6

Carbon element

 Evgeny Gromov / Getty Images

Carbon the element that is atomic number 6 on the periodic table. This nonmetal is the basis for life as we know it. It's familiar as a pure element, as diamond, graphite, and charcoal.

Fast Facts: Atomic Number 6

  • Element Name: Carbon
  • Atomic Number: 6
  • Element Symbol: C
  • Atomic Weight: 12.011
  • Element Group: Group 14 (Carbon Family)
  • Category: Nonmetal or Metalloid
  • Electron Configuration: [He] 2s2 2p2
  • Phase at STP: Solid
  • Oxidation States: Usually +4 or -4, but also +3, +2, +1, 0, -1, -2, -3
  • Discovery: Known to the Egyptians and Sumerians (3750 BCE)
  • Recognized as an Element: Antoine Lavoisier (1789)
Forms of the element carbon
Element atomic number 6 is carbon. Forms of pure carbon include diamond, graphite, and amorphous carbon. Dave King / Getty Images

Element Atomic Number 6 Facts

  • Each atom of carbon has 6 protons and electrons. The element naturally exists as a mix of three isotopes. Most of this carbon has 6 neutrons (carbon-12), plus there are small amounts of carbon-13 and carbon-14. Carbon-12 and carbon-13 are stable. Carbon-14 is used for radioisotope dating of organic material. A total of 15 isotopes of carbon are known.
  • Pure carbon can take any of several different forms, called allotropes. These allotropes exhibit markedly different properties. For example, diamond is the hardest form of any element, while graphite is very soft, and graphene is stronger than steel. Diamond is transparent, while other forms of carbon are opaque gray or black. All of the allotropes of carbon are solids at room temperature and pressure. The discovery of the allotrope fullerene won the Nobel Prize in Chemistry in 1996.
  • The element name carbon comes from the Latin word carbo, which means coal. The element symbol for atomic number 6 is C. Carbon is among the elements known in pure form by ancient mankind. Primitive man used carbon in the forms of soot and charcoal. The Chinese knew of diamonds as early as 2500 BCE. Credit for the discovery of carbon as an element is given to Antoine Lavoisier. In 1772, he burned samples of diamond and charcoal and proved each released the same amount of carbon dioxide per gram.
  • Carbon has the highest melting point of the pure elements at 3500 °C (3773 K, 6332 °F).
  • Carbon is the second most abundant element in humans, by mass (after oxygen). Approximately 20% of the mass of a living organism is atomic number 6.
  • Carbon is the fourth most abundant element in the universe. The element forms in stars via the triple-alpha process in which helium atoms fuse to form atomic number 4 (beryllium), which then fuses with atomic number 2 (helium) to form atomic number 6.
  • Carbon on Earth is constantly recycled via the Carbon Cycle. All of the carbon in your body once existed as carbon dioxide in the atmosphere.
  • Pure carbon is considered non-toxic, although inhaling it can cause lung damage. Carbon particles in the lung may irritate and abrade lung tissue, potentially leading to lung disease. Because the carbon particles resist chemical attack, they tend to remain in the body (except the digestive system) indefinitely. Pure carbon, in the forms of charcoal or graphite, may be safely ingested. It has been used since prehistoric time for making tattoos. The tattoos of Otzi the Iceman, a 5300-year-old frozen corpse, were likely made using charcoal.
  • Carbon is the basis for the organic chemistry. Living organisms contain four classes of organic molecules: nucleic acids, fats, carbohydrates, and proteins.
  • The reason element atomic number 6 is so important for life is because of its electron configuration. It has four valence electrons, but the p-shell is most stable when it is full (octet) or empty, giving carbon a usual valence of +4 or -4. With four binding sites and a relatively small atomic size, carbon can form chemical bonds with a wide variety of other atoms or functional groups. It's a natural pattern maker, able to form polymers and complex molecules.
  • While pure carbon is non-toxic, some of its compounds are lethal poisons. These include ricin and tetrodotoxin.
  • In 1961, the IUPAC adopted the isotope carbon-12 as the basis for the atomic weight system.


  • Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. ISBN 0-08-037941-9.
  • Hammond, C. R. (2004). The Elements, in Handbook of Chemistry and Physics (81st ed.). CRC press. ISBN 978-0-8493-0485-9.
  • Lide, D. R., ed. (2005). CRC Handbook of Chemistry and Physics (86th ed.). Boca Raton (FL): CRC Press. ISBN 0-8493-0486-5.
  • Weast, Robert (1984). CRC, Handbook of Chemistry and Physics. Boca Raton, Florida: Chemical Rubber Company Publishing. pp. E110. ISBN 0-8493-0464-4.
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Helmenstine, Anne Marie, Ph.D. "Atomic Number 6 - Carbon or C." ThoughtCo, Sep. 7, 2021, Helmenstine, Anne Marie, Ph.D. (2021, September 7). Atomic Number 6 - Carbon or C. Retrieved from Helmenstine, Anne Marie, Ph.D. "Atomic Number 6 - Carbon or C." ThoughtCo. (accessed June 2, 2023).