Which statement is true about single elements and oxidation state?

Which statement is true about single elements and oxidation state?

• A. They always have +1
• B. Single elements have zero oxidation state
• C. They can have any value depending on the element
• D. They have -2

Answer: (B)

Oxidation state is a way to assign a hypothetical charge to atoms to keep track of electron transfer in reactions. For any element in its pure, uncombined form, there is no net charge and no transfer of electrons with other species, so its oxidation state is zero. This holds true for single atoms and for molecules made of the same element, like O2 or N2—the oxidation state of each atom is still zero. The idea that a single element must have +1 or -2 ignores this baseline rule. Elements take on positive or negative oxidation numbers only within compounds, where electrons are effectively transferred or shared in ways that give those formal charges (for example, hydrogen is typically +1 in many compounds, oxygen is typically -2, though there are exceptions).

Oxidation state is a way to assign a hypothetical charge to atoms to keep track of electron transfer in reactions. For any element in its pure, uncombined form, there is no net charge and no transfer of electrons with other species, so its oxidation state is zero. This holds true for single atoms and for molecules made of the same element, like O2 or N2—the oxidation state of each atom is still zero. The idea that a single element must have +1 or -2 ignores this baseline rule. Elements take on positive or negative oxidation numbers only within compounds, where electrons are effectively transferred or shared in ways that give those formal charges (for example, hydrogen is typically +1 in many compounds, oxygen is typically -2, though there are exceptions).