The classification of particles according to quantum numbers arising from the rotational symmetries of strong and weak interaction in a seven dimensional isospace is presented. In all practical cases for strong interactions, this seven dimensional space splits into a four dimensional and a three dimensional independent isospaces similar to those proposed by \textit{J. Tiomno} [Nouvo Cimento 6, 69--83 (1957)] and other authors. The baryon is considered as a single spinor with eight different charge states. The strong \( K \) baryon interactions are represented by rotations in the four dimensional isospace; should all the baryon masses be equal, two independent constants of the motion should exist, total hypercharge \( Y \) and total \( K \)-interaction isospin \( U \). The strong pion baryon interactions are represented by rotations in the three dimensional isospace in the usual way; the constant of the motion being in this case the total pion isospin, \( T. I=T+U \) represents the total isospin for all strong interactions which is conserved when electromagnetic interactions are neglected. Conservation of total hypercharge \( Y \) is destroyed by the baryon mass differences and only the third component of it \( Y_{3} \) is a constant (usual hypercharge). The \( N-\Xi \) mass difference is assumed to be intrinsic (not explained by the interaction), while the \( \Lambda-\Sigma \) mass difference is assumed to be due to a perturbation of a two boson two fermion type. The leptons are also classified in order to form an eight spinor including two different kinds of neutrinos. It is attempted to use the properties of the seventh dimensional isospace in order to formulate an universal Fermi interaction and explain the weak selection rules.