To determine the number of lone pairs around the central atom in CH2Cl2 (dichloromethane), we first need to identify the central atom. In this molecule, carbon (C) is the central atom, surrounded by two hydrogen (H) atoms and two chlorine (Cl) atoms.
The first step is to count the total number of valence electrons. Carbon has 4 valence electrons, each hydrogen has 1 (for a total of 2 from two hydrogens), and each chlorine has 7 (for a total of 14 from two chlorines). Adding these together:
- 4 (C) + 2 (H) + 14 (Cl) = 20 valence electrons
Next, we arrange the electrons around the central carbon atom. Carbon will form four bonds: two with the hydrogen atoms and two with the chlorine atoms. This accounts for 8 of the 20 valence electrons (2 electrons per bond).
- 8 electrons used for bonding (4 bonds)
- Remaining electrons: 20 – 8 = 12 electrons
Now, we will distribute the remaining 12 electrons. We place 6 electrons (3 pairs) around each chlorine atom (since chlorine needs 8 electrons to satisfy the octet rule), using up 12 electrons.
Now let’s look at the carbon atom again. It has formed four bonds (two C-H and two C-Cl) and has no remaining unbonded electrons. Therefore, there are no lone pairs on the carbon atom.
In summary, the central atom in CH2Cl2, which is carbon, has 0 lone pairs around it.