  We present a model for describing flexible polyelectrolytes in a good solvent
a nd in the presence of monovalent salt . The molecule composed by $N$ monomers
is characterized by the end to end distanc e $R_e=b (Z-1)^\gamma$ and the
number of associated counterions $n$. At high tem peratures the polyelectrolyte
behaves as a neutral polymer ($\gamma=0.588$). Dec reasing the temperature, the
macromolecule changes from this extended configurat ion($\gamma=0.588$) to a
stretched form ($\gamma\approx 1$). At even lower temp eratures, above the
Manning condensation threshold, the polyelectrolyte collapse s ($\gamma\approx
0.3$). Our results show good agreement with simulations.
