Formaldehyde has the chemical formula CH2O. How many electrons must be shown in the Lewis structure of formaldehyde?
a) 4
b) 8
c) 12
d) 16
To determine the number of electrons needed for the Lewis structure of formaldehyde, we need to count the valence electrons of each atom in the molecule.
Carbon (C) is in group 4, so it has 4 valence electrons.
Hydrogen (H) is in group 1, so it has 1 valence electron.
Oxygen (O) is in group 6, so it has 6 valence electrons.
The Lewis structure of formaldehyde (CH2O) will consist of a carbon atom bonded to two hydrogen atoms and an oxygen atom.
Carbon (C) will form 4 bonds, using 1 of its valence electrons for each bond. Therefore, carbon will contribute 4 electrons to the Lewis structure.
Hydrogen (H) will each form 1 bond, using 1 of their valence electrons for the bond. Therefore, the two hydrogen atoms will contribute 2 electrons to the Lewis structure.
Oxygen (O) will form 2 bonds, using 2 of its valence electrons for those bonds. Therefore, oxygen will contribute 2 electrons to the Lewis structure.
Adding up the contributions from each atom, we have a total of 4 + 2 + 2 = 8 electrons.
Therefore, the Lewis structure of formaldehyde must show 8 electrons. The correct answer is (b) 8.