Carbon
Carbon (C) is a reactive nonmetal with atomic number 6 and an atomic mass of 12.011. Its electron configuration is [He] 2s2 2p2, which gives it 4 valence electrons.
Carbon key data
| Symbol | C |
|---|---|
| Atomic number | 6 |
| Atomic mass (standard atomic weight) | 12.011 |
| Molar mass | 12.011 g/mol |
| Protons | 6 |
| Neutrons (most abundant isotope, carbon-12) | 6 |
| Electrons (neutral atom) | 6 |
| Valence electrons | 4 |
| Category | Reactive nonmetal |
| Period | 2 |
| Group | 14 |
| Block | p-block |
| Noble gas notation | [He] 2s2 2p2 |
| Full electron configuration | 1s2 2s2 2p2 |
| Electrons per shell | 2, 4 |
Atomic mass: IUPAC CIAAW abridged standard atomic weights, 2024. Most abundant isotope: NIST Atomic Weights and Isotopic Compositions.
The values are facts and free to use; this page’s selection and presentation are © 2026 ScienceQuest.
Measured properties of carbon
From PubChem, the US National Institutes of Health. Public domain.
| Melting point (PubChem’s figure; graphite melts only under pressure, at about 4600 to 4800 K) | 3823 K (3549.9 °C), 1st of 103 by melting point |
|---|---|
| Sublimation point | 4098 K (3824.9 °C), joint 16th of 93 by boiling point |
| Density | 2.267 g/cm³, 75th of 96 by density |
| State at room temperature | Solid |
| Electronegativity | 2.55 (Pauling), joint 10th of 95 by electronegativity |
| Van der Waals radius | 170 pm, 87th of 99 by atomic radius |
| First ionisation energy | 11.26 eV (1086 kJ/mol), 12th of 102 by first ionisation energy |
| Electron affinity | 1.263 eV (121.9 kJ/mol), 16th of 57 by electron affinity |
| Common oxidation states | +4, +2, −4 |
| Discovered | Ancient |
Each rank counts down from the highest value, among the elements PubChem’s table gives one for, and links to that property ranked across the whole table. All of them are collected under periodic trends.
Carbon electron configuration
The full electron configuration of carbon is 1s2 2s2 2p2. With the noble-gas core collapsed it is [He] 2s2 2p2, and the outermost subshell is 2p2.
Why group and block follow from this is set out in how the periodic table maps electron configuration, and the electron configuration of every element is listed on one page.
Mass of one carbon atom
A molar mass is grams per mole, so dividing by the Avogadro constant gives the mass of a single atom, or for an element with more than one natural isotope the average mass of its atoms, and the reciprocal gives how many atoms sit in a gram.
Mass of one atom
- one atom = 12.011 / (6.02214076 × 10²³)
- = 1.9945 × 10⁻²³ g
Atoms in one gram
- atoms per gram = 6.02214076 × 10²³ / 12.011
- = 5.0139 × 10²² atoms
Carbon on the periodic table
Carbon is in period 2, group 14, in the p-block.
The other elements of group 14 are silicon, germanium, tin, lead and flerovium.