The formate ion, HCO₂⁻, is formed when formic acid dissolves in water. A number of possible resonance structures for this ion are shown. Which of these structures are valid and which are invalid?

Sulfur tetrafluoride (SF₄) reacts slowly with O₂ to form sulfur tetrafluoride monoxide (OSF₄) according to the following unbalanced reaction: SF₄(g) + O₂(g) → OSF₄(g) The O atom and the four F atoms in OSF₄ are bonded to a central S atom. (b) Write a Lewis structure of OSF₄ in which the formal charges of all atoms are zero.

Draw the Lewis structures for three resonance forms of the nitrate ion, NO3⁻. Include electron lone pairs, and any formal charges.

Draw the Lewis structures for three resonance forms of the nitrate ion, NO^-3. Include electron lone pairs, and any formal charges.

What features do all the resonance forms of a molecule or ion have in common?