**2. Basic structure of carbon**

Carbon is foremost exciting element in periodic table to chemists because of its electrical structure and atomic size [6].

#### **2.1 Electronic and nuclei configuration of the carbon atom**

Carbon's symbol is C, and its atomic number (Z) is 6, indicating that the neutral carbon atom (C-12 isotope) contains six protons and six neutrons in its nucleus and likewise, six electrons in its electronic shells. 1s2 2s2 2p2 is the electron configuration or the electronic arrangement in each orbital [2].

#### **2.2 Atomic mass (atomic weight) of carbon**

The basis for establishing the atomic mass unit is the element carbon. By definition, an atomic mass unit is 1/12th of the atomic mass of the (C-12) isotope. The "International Union of Pure and Applied Chemistry approved" this concept in 1961. The atomic mass unit is absolutely, incredibly small in comparison to the traditional definition of a mass: one gram requires 0.6022 × 1024 amu (also known as Avogadro's number or NA). Natural carbon has 98.89 percent 12C and only 1.11 percent of 13C. Consequently, the average carbon atom's atomic mass is 12.01115 amu.

#### **2.3 Carbon's radius**

Carbon's atomic radius is half the gap between two carbon atoms in a planar graphite lattice. When compared to other elements (H, Li, He, B, Be, O, N, F), carbon has one of the shortest radii. Carbon has seven different isotopes out of which three isotopes have been identified (12C, 13C, 14C). The isotope 12C, which possesses six neutrons, is by far the most abundant. There are four to ten neutrons in the others (10C to 16C). C-12 and C-13 are the most stable isotopes of carbon, meaning they do not dissolve or change structure spontaneously. The other five-carbon nuclei are radioactive, which means they decay naturally by emitting particles, which are maybe an electron (β<sup>−</sup> ) or a positron (β<sup>+</sup> ) and are formed by neutron splitting [2]. In the study of organic reactions, the radioactive isotope 14C is used as a tracer. The magnetic moment (spin V2) of 13C makes it an appropriate probe for NMR research. For the atomic mass unit, 12C is utilized as the reference definition because of its enormous abundance and an emerging power. It is defined as having the Relative Atomic Mass of 12 precisely. This definition now governs all other nuclei and molecular masses [9].
