# How many electrons are shared in the Lewis structure of CH_2Cl_2?

Well, clearly, there are 4 covalent bonds, and thus the number of shared electrons is $8$.
We look at the electronic structure of atomic carbon, hydrogen, and chlorine. Around the central carbon atom there are 4 valence electrons; these are shared with 2 hydrogens to form $2 \times C - H$ bonds, and with two chlorine atoms, to form $2 \times C l$ bonds.