Question

shape of becl4^2-

Answer 1

Be has 2 valence electrons, and the Cl are each willing to share 1, and you have 2 extra because of the -2 charge, for a total of 2 + 4 x 1 + 2 = 8 electrons, or 4 pairs.

4 pairs around the central Be will naturally get as far apart from each other as they can, which means you have a tetrahedral arrangement of Be-Cl bonds.