  We present the abundance analysis of stars from the tip of the red giant
branch (RGB) to below the RGB-bump in the globular cluster NGC 2808, based on
high resolution echelle spectra. We derived abundances of Al, alpha-process
elements (Si I, Ca I, Ti I and Ti II) and Fe-group elements (Sc II, V I, Cr I,
Cr II, Mn I, Co I, Ni I). Apart from Mg being somewhat reduced, likely because
it has been depleted at the expense of Al in the MgAl cycle, the other
alpha-element ratios show the overabundance typical of halo stars of similar
metallicity. Mn is underabundant, whereas Fe-group elements have typical
abundance ratios near the solar value. We detect star-to-star differences in Al
abundances from the RGB tip down to the faintest star below the RGB-bump,
correlated with Na abundances at all luminosities. The slope of the Na-Al
correlation is similar to the one found in M 13 by Sneden et al. (2004), but it
is different from those in other globular clusters of similar metallicity. We
find that the amount of chemical inhomogeneities along the Na-O and Mg-Al
anticorrelations in globular cluster red giants is correlated with the present
day cluster mass and ellipticity. Moreover, we find for the first time a
correlation between the spread in proton-capture elements and orbital
parameters of clusters. The chemical anomalies are more extended in clusters
having large-sized orbits and longer periods, and in clusters with larger
inclination angles of the orbit with respect to the Galactic plane.
