Final answer:
To draw the Lewis structure of formaldehyde, place the carbon atom in the center, connect it to two hydrogens with single bonds and to oxygen with a double bond. Include two lone pairs on oxygen to fulfill the octet rule.
Step-by-step explanation:
To draw the Lewis structure for formaldehyde (CH₂O), start by placing the carbon (C) atom in the center since it is the least electronegative atom compared to hydrogen (H) and oxygen (O). Connect the carbon atom to two hydrogen atoms with single bonds and to the oxygen atom with a double bond. The double bond accounts for two pairs of shared electrons. The oxygen atom will also have two lone pairs of electrons that are not shared with the carbon atom. This arrangement gives both carbon and oxygen atoms a stable octet of electrons, resulting in a trigonal planar molecular shape around the carbon atom, as all three electron groups around carbon repel each other equally.