The level density and the thermodynamic quantities for 2 98 56𝐶 heavy, and 11 29 4 0𝐹 super heavy isotopes have been calculated using an improved version of the back sifted Fermi gas model including the temperature dependent level density parameter, the pairing energy, and the shell effects. The single- particle level density parameter for 2 98 56𝐶 heavy and 11 29 4 0𝐹 super heavy isotopes have been calculated using a semi-classical method, taking into account the Woods-Saxon potential for the interaction of nucleons inside the nucleus based on the single-particle Fermi gas model. A power series up to third degree are considered for energy as a function of temperature instead of square of temperature in the simple back shifted Fermi gas model. The calculated level density parameters are used to obtain the level density and the thermodynamic quantities of these isotopes such as the entropy, the temperature, and the heat capacity. The obtained results for these isotopes as a function of excitation energies were compared. The variation of the heat capacity as a function of the excitation energy shows the breaking of the first nucleon pair, which occurs at energies � = 2.948 𝑀� and � = 3.04 𝑀� for 2 9856𝐶 heavy and 11 294 0𝐹 super heavy isotopes, respectively.
