  We investigate the effects of Pauli blocking on the properties of hydrogen at
high pressures, where recent experiments have shown a transition from
insulating behavior to metal-like conductivity. Since the Pauli principle
prevents multiple occupation of electron states (Pauli blocking), atomic states
disintegrate subsequently at high densities (Mott effect). We calculate the
energy shifts due to Pauli blocking and discuss the Mott effect solving an
effective Schroedinger equation for strongly correlated systems. The ionization
equilibrium is treated on the basis of a chemical approach. Results for the
ionization equilibrium and the pressure in the region 4.000 K < T < 20.000 K
are presented. We show that the transition to a highly conducting state is
softer than found in earlier work. A first order phase transition is observed
at T < 6.450 K, but a diffuse transition appears still up to 20.000 K.
