  We study the distribution, masses, and dynamical properties of galaxy groups
in the A2142 supercluster. We analyse the global luminosity density
distribution in the supercluster and divide the supercluster into the
high-density core and the low-density outskirts regions. We find galaxy groups
and filaments in the regions of different global density, calculate their
masses and mass-to-light ratios and analyse their dynamical state with several
1D and 3D statistics. We use the spherical collapse model to study the
dynamical state of the supercluster. We show that in A2142 supercluster groups
and clusters with at least ten member galaxies lie along an almost straight
line forming a 50 Mpc/h long main body of the supercluster. The A2142
supercluster has a very high density core surrounded by lower-density outskirt
regions. The total estimated mass of the supercluster is M_est = 6.2
10^{15}M_sun. More than a half of groups with at least ten member galaxies in
the supercluster lie in the high-density core of the supercluster, centered at
the rich X-ray cluster A2142. Most of the galaxy groups in the core region are
multimodal. In the outskirts of the supercluster, the number of groups is
larger than in the core, and groups are poorer. The orientation of the cluster
A2142 axis follows the orientations of its X-ray substructures and radio halo,
and is aligned along the supercluster axis. The high-density core of the
supercluster with the global density D8 > 17 and perhaps with D8 > 13 may have
reached the turnaround radius and started to collapse. A2142 supercluster with
luminous, collapsing core and straight body is an unusual object among galaxy
superclusters. In the course of the future evolution the supercluster may be
split into several separate systems.
