Changes in neutron shell closures of light very neutron-rich nuclei

We present a review of experimental studies on the properties of extremely neutron-rich nuclei (Z = 6-20, A = 20-60) near the neutron drip line. Recen t data on mass measurements of neutron-rich nuclei at, GANIL, (Caen, France ) and some characteristics of binding energies in this region are discussed . Being sensitive to the existence of nuclear shells separation energies S- 2n together with the evidence of particle instability of doubly magic nucle i He-10 and O-28 could provide information on changes in shell closures. Pa rticularly opening of an N = 16 shell and vanishing of the N = 20 shell for very neutron-rich isotopes is under discussion. Decay studies of these har dly accessible short-lived neutron-rich nuclei from oxygen to silicon using the in-beam gamma -ray spectroscopy are also reported.