Here's how to determine the number of valence electrons in CH2Cl2 (dichloromethane):

* Valence Electrons per Atom:

* Carbon (C): 4 valence electrons

* Hydrogen (H): 1 valence electron

* Chlorine (Cl): 7 valence electrons

* Total Valence Electrons:

* (1 Carbon x 4 valence electrons) + (2 Hydrogen x 1 valence electron) + (2 Chlorine x 7 valence electrons) = 20 valence electrons

Therefore, CH2Cl2 has 20 valence electrons.