Here's why:
* Electronegativity: Oxygen is more electronegative than sulfur. This means oxygen has a stronger attraction for electrons.
* Sharing Electrons: The difference in electronegativity isn't large enough to cause a complete transfer of electrons (which would create an ionic bond). Instead, the sulfur and oxygen atoms share electrons to form covalent bonds.
Examples:
* Sulfur dioxide (SO2): Two covalent bonds exist between each sulfur atom and each oxygen atom.
* Sulfur trioxide (SO3): Three covalent bonds exist between each sulfur atom and each oxygen atom.
Important Note: While the bonds are primarily covalent, due to the difference in electronegativity, they often have a degree of polarity. This means the electrons are not shared equally, leading to a slight negative charge on the oxygen atoms and a slight positive charge on the sulfur atom.
