When comparing two oxyacids with two different heteroatoms, the more _________ heteroatom, the more acidic the oxyacid.

When comparing two oxyacids with two different heteroatoms, the more _________ heteroatom, the more acidic the oxyacid.

• A. Atomic mass
• B. Electronegative
• C. Size
• D. Position in periodic table

Answer: (B)

The effect being tested is how well the conjugate base of an oxyacid is stabilized. The more electronegative the heteroatom attached to the oxygens, the stronger the acid. Electronegative atoms pull electron density away through the bonds to oxygen, which helps stabilize the negative charge that remains on the conjugate base after deprotonation. Because this stabilization lowers the energy of the conjugate base, the equilibrium favors dissociation more, making the acid stronger. Atomic mass or size don’t directly govern this stabilization, and while electronegativity often follows periodic trends, it’s the electronegativity itself that matters for the acidity of oxyacids.

The effect being tested is how well the conjugate base of an oxyacid is stabilized. The more electronegative the heteroatom attached to the oxygens, the stronger the acid. Electronegative atoms pull electron density away through the bonds to oxygen, which helps stabilize the negative charge that remains on the conjugate base after deprotonation. Because this stabilization lowers the energy of the conjugate base, the equilibrium favors dissociation more, making the acid stronger.

Atomic mass or size don’t directly govern this stabilization, and while electronegativity often follows periodic trends, it’s the electronegativity itself that matters for the acidity of oxyacids.