Variation of thermomagnetic properties of nanoparticles are the matter of great debate. To develop a suitable model for the study of magnetic properties, the size and shape dependent magnetic properties such as Curie temperature (TC), Neel temperature (TN) and magnetization (MS) of magnetic nanoparticles (Fe, Ni, Co, Fe3O4, NiO, CoO, CuO, Ho and CoFe2O4) have been studied. In the present work, bond energy model has been used with the concept of dangling bond and its effect on the surface of nanoparticles. It is observed that the introduction of packing fraction of materials to this model supports the experimental facts. The obtained results have been explained by considering the concept of dangling bond at the surface of nanoparticle and packing fraction of crystal. It is observed that these magnetic properties decrease with reducing size of nanoparticles and the available experimental data are in good agreement with present theoretical model. The validity of present model encourages us to predict the behaviour of thermomagnetic properties of other nanoparticles.