H2Se adopts a “bent” structure with a H-Se-H bond angle of 91°.
You can make useful comparision with H-O-H [H2O] and H-SH [H2S]. To explain this, it would be important for you to understand hybridization theory. The bond angle of H-O-H is 105, and that of H- S-H is 92. This would suggest that S is hardly hybridized at all, and in fact using p-orbitals (with little s-characteristics) to form the S-H bonds, whereas O is sp3 hybridized.
To understand why S is not hybridized, we need to understand that the large size of S allows the electron pairs to be far from each other so that the energy incurred from repulsion is not very large and need not be minimized. Since O is a lot smaller, a more stable, less energetic configuration, would have to be made – hence the hybridization.
Each of the molecules H2O, H2Se, H2Te has two lone, non-bonding pairs of electrons. They originate from the atoms O, Se, Te which are in successive rows of the periodic table. As a result the electron pairs are attracted by the nuclei less and less strongly. As a consequence of this lower attraction the lone pairs occupy more space. This in turn causes the bond angle of the H’s to become more acute. This reasoning is just one example of a semi-empirical bonding model called: Valence Shell Electron Pair Repulsion (VSEPR).
Seh2 Lewis Structure
try google it.