Application of isotopes in carbon dating
Its first four ionisation energies, 1086.5, 2352.6, 4620..7 k J/mol, are much higher than those of the heavier group 14 elements.
The electronegativity of carbon is 2.5, significantly higher than the heavier group 14 elements (1.8–1.9), but close to most of the nearby nonmetals as well as some of the second- and third-row transition metals.
Although thermodynamically prone to oxidation, carbon resists oxidation more effectively than elements such as iron and copper that are weaker reducing agents at room temperature.
Carbon is the sixth element, with a ground-state electron configuration of 1s, of which the four outer electrons are valence electrons.
For example, graphite is opaque and black while diamond is highly transparent.
Graphite is soft enough to form a streak on paper (hence its name, from the Greek verb "γράφειν" which means "to write"), while diamond is the hardest naturally occurring material known.
Carbon's covalent radii are normally taken as 77.2 pm (C–C), 66.7 pm (C=C) and 60.3 pm (C≡C), although these may vary depending on coordination number and what the carbon is bonded to.
Under normal conditions, diamond, carbon nanotubes, and graphene have the highest thermal conductivities of all known materials.
Once considered exotic, fullerenes are nowadays commonly synthesized and used in research; they include buckyballs, The amorphous form is an assortment of carbon atoms in a non-crystalline, irregular, glassy state, not held in a crystalline macrostructure.
It is present as a powder, and is the main constituent of substances such as charcoal, lampblack (soot) and activated carbon.
The system of carbon allotropes spans a range of extremes: Atomic carbon is a very short-lived species and, therefore, carbon is stabilized in various multi-atomic structures with different molecular configurations called allotropes.
The three relatively well-known allotropes of carbon are amorphous carbon, graphite, and diamond.