Draw Lewis structures for the following: $(\mathbf{a}) \mathrm{CH}_{2} \mathrm{Cl}_{2},(\mathbf{b}) \mathrm{ClCN},\( (c) \)\mathrm{AsF}_{5}$ (d) \(\mathrm{CH}_{2} \mathrm{O}\) (C the central atom), (e) \(\mathrm{OF}_{2}\) (f) \(\mathrm{NO}_{3}^{-}\).

For each of the given compounds, the central atom should be the least electronegative element, except in the case of hydrogen (since hydrogen can only form one bond). The central atoms for each compound are as follows: - a) CH2Cl2: Carbon (C) - b) ClCN: Carbon (C) - c) AsF5: Arsenic (As) - d) CH2O: Carbon (C) - e) OF2: Oxygen (O) - f) NO3-: Nitrogen (N)

Now, we will find the total number of valence electrons for each compound. This can be done by adding up the number of valence electrons for each element and, in the case of ions, adding or subtracting the respective number of electrons. - a) CH2Cl2: 4 (C) + 2(1) (H) + 2(7) (Cl) = 20 valence electrons - b) ClCN: 7 (Cl) + 4(C) + 5(N) = 16 valence electrons - c) AsF5: 5 (As) + 5(7) (F) = 40 valence electrons - d) CH2O: 4 (C) + 2(1) (H) + 6 (O) = 12 valence electrons - e) OF2: 6 (O) + 2(7) (F) = 20 valence electrons - f) NO3-: 5 (N) + 3(6) (O) + 1 (extra electron from the negative charge) = 24 valence electrons

Now, for each compound, we will arrange the electrons around the atoms in a way that satisfies the octet rule, keeping in mind that hydrogen only needs two electrons to have a full shell. - a) CH2Cl2: 1. Start with Carbon in the center. 2. Place two Hydrogen atoms and two Chlorine atoms around the Carbon in a tetrahedral configuration. 3. Connect each surrounding atom to the Carbon with single bonds. This uses 8 of the 20 valence electrons. 4. Fill the octets of the surrounding atoms with the remaining 12 valence electrons (6 pairs). - b) ClCN: 1. Start with Carbon in the center. 2. Place Chlorine and Nitrogen atoms on either side of the Carbon. 3. Connect the Chlorine and the Nitrogen to the Carbon with single bonds. This uses 4 of the 16 valence electrons. 4. Fill the octet of Chlorine with 6 more valence electrons (3 pairs). 5. Place the remaining 6 valence electrons (3 pairs) on the Nitrogen atom to form a triple bond between the Nitrogen and Carbon. - c) AsF5: 1. Place Arsenic in the center. 2. Surround it with five Fluorine atoms. 3. Connect each Fluorine to the Arsenic with single bonds. This uses 10 of the 40 valence electrons. 4. Fill the octets of the surrounding Fluorine atoms with the remaining 30 valence electrons (15 pairs). - d) CH2O: 1. Start with Carbon in the center. 2. Place two Hydrogen atoms and one Oxygen atom around the Carbon in a trigonal planar configuration. 3. Connect each surrounding atom to the Carbon with single bonds. This uses 6 of the 12 valence electrons. 4. Place the remaining 6 valence electrons (3 pairs) around the Oxygen atom, forming a double bond between Carbon and Oxygen. - e) OF2: 1. Place Oxygen in the center. 2. Place two Fluorine atoms around the Oxygen in a linear configuration. 3. Connect each Fluorine to the Oxygen with single bonds. This uses 4 of the 20 valence electrons. 4. Fill the octets of the surrounding atoms with the remaining 16 valence electrons (8 pairs). - f) NO3-: 1. Start with Nitrogen in the center. 2. Place three Oxygen atoms around the Nitrogen in a trigonal planar configuration. 3. Connect each Oxygen to the Nitrogen with single bonds. This uses 6 of the 24 valence electrons. 4. Fill the octets of two surrounding Oxygen atoms with 12 more valence electrons (6 pairs). 5. Place the remaining 6 valence electrons (3 pairs) around one Oxygen atom, forming a double bond between that Oxygen and Nitrogen. In conclusion, we have drawn the Lewis structures for all six compounds by identifying the central atom, finding the total number of valence electrons, and arranging the electrons around the atoms in a way that satisfies the octet rule.