Chemical Properties The atomic number of carbon is 6. The atomic mass of carbon is 12.011 g. ... The density of the carbon atom is 2.2 g. ... The melting and boiling point of carbon is 3652 °C and 4827 °C, respectively. The Van der Waals radius is 0.091 nm. The Ionic radius of the carbon atom is 0.015 nm (+4); 0.26 nm (-4). More items...