  We present a comprehensive study of the evolution of the abundances of
intermediate mass elements, from C to Zn, in the Milky Way halo and in the
local disk. We use a consistent model to describe the evolution of those two
galactic subsystems. The halo and the disk are assumed to evolve independently,
both starting with gas of primordial composition, and in different ways: strong
outflow is assumed to take place during the $\sim$1 Gyr of the halo formation,
while the disk is built by slowly infalling gas. This description of the
halo+disk evolution can correctly account for the main observational
constraints (at least in the framework of simple models of galactic chemical
evolution). We utilise then metallicity dependant yields to study the evolution
of all elements from C and Zn. Comparing our results to an extensive body of
observational data (including very recent ones), we are able to make a critical
analysis of the successes and shortcomings of current yields of massive stars.
Finally, we discuss qualitatively some possible ways to interpret the recent
data on oxygen vs iron, which suggest that oxygen behaves differently from the
other alpha-elements.
