The decay chains of several isotopes of yet-unaccessible superheavy elements Z = 119 - 122 are predicted from the analysis of the emitted particles or heavy fragments. The ground state-to-ground state α-rates have been theoretically calculated by using the microscopic shell model (SM) and ”one-body” (ob) resonance α-overlap integrals. We have estimated the α and spontaneous fission (SF) rates by using empirical formulas deduced from the systematics of known experimental decay data for Z = 104-118 nuclei. The obtained results are discussed and compared with other predictions. From a detailed analysis of calculated α-rates and SF-rates we get that the quantum shell effects and finite sizes of nucleons and clusters have an important role in providing extra stability to the doubly magic nucleus {292}120. The spectroscopic information is deduced from the ratio of SM and ob α-rates calculated with and without shell structure effects.