Input interpretation
guanine | structure diagram
Result
Draw the Lewis structure of guanine. Start by drawing the overall structure of the molecule, ignoring potential double and triple bonds: Count the total valence electrons of the carbon (n_C, val = 4), hydrogen (n_H, val = 1), nitrogen (n_N, val = 5), and oxygen (n_O, val = 6) atoms: 5 n_C, val + 5 n_H, val + 5 n_N, val + n_O, val = 56 Calculate the number of electrons needed to completely fill the valence shells for carbon (n_C, full = 8), hydrogen (n_H, full = 2), nitrogen (n_N, full = 8), and oxygen (n_O, full = 8): 5 n_C, full + 5 n_H, full + 5 n_N, full + n_O, full = 98 Subtracting these two numbers shows that 98 - 56 = 42 bonding electrons are needed. Each bond has two electrons, so in addition to the 17 bonds already present in the diagram add 4 bonds. To minimize formal charge carbon wants 4 bonds, nitrogen wants 3 bonds, and oxygen wants 2 bonds. Identify the atoms that want additional bonds and the number of electrons remaining on each atom: Fill in the 4 bonds by pairing electrons between adjacent highlighted atoms: Answer: | |