Account for each of the following observations.
b. SF₄ exists, but OF₄ does not.

VSEPR theory is used to predict the geometry of molecular structures based on the repulsion between electron pairs around a central atom. In the case of SF4, the sulfur atom has six valence electrons, allowing it to form four bonds with fluorine and maintain a stable structure with a seesaw shape. Conversely, OF4 would require oxygen to accommodate four bonds, which is not feasible due to its limited valence electrons.

Electronegativity refers to the tendency of an atom to attract electrons in a bond. Sulfur is less electronegative than fluorine, allowing SF4 to form stable covalent bonds. In contrast, oxygen is more electronegative than sulfur, leading to instability in OF4 as the oxygen atom would struggle to form four stable bonds without exceeding its octet.

The octet rule states that atoms tend to form bonds in such a way that they have eight electrons in their valence shell, achieving a stable electron configuration. SF4 adheres to this rule, while OF4 does not, as oxygen can only accommodate a maximum of two additional electrons in its valence shell, making the formation of OF4 energetically unfavorable and unstable.