The electron dot structure for sulfur trioxide (SO3) can be drawn by following the steps of valence electron counting and bonding. Sulfur (S) is in group 16 and has six valence electrons, while each oxygen (O) atom also has six valence electrons. In SO3, one sulfur atom is bonded to three oxygen atoms.
To form the structure, we start with the sulfur atom at the center, surrounded by three oxygen atoms. Each S-O bond is a double bond, which means that two pairs of electrons are shared between sulfur and each oxygen. Therefore, we distribute the electrons accordingly:
- S has a total of 6 valence electrons.
- Each O will also have adjacent lone pairs to fulfill the octet rule.
This results in one central sulfur atom bonded to three oxygen atoms via double bonds, with each oxygen atom holding two additional lone pairs of electrons.
In terms of molecular shape, SO3 adopts a trigonal planar geometry. This arrangement occurs due to the repulsion between the electron pairs, which spread out to be as far apart as possible.
As for polarity, SO3 is classified as a nonpolar molecule. Although there are polar covalent bonds between the sulfur and oxygen atoms, the symmetrical trigonal planar shape means that the dipoles cancel out, resulting in no overall dipole moment. Therefore, the molecule does not have a positive or negative end, which makes it nonpolar.
In summary, the electron dot structure of SO3 shows double bonds between sulfur and each oxygen, leading to a trigonal planar molecular shape that is nonpolar.