Final answer:
The picture representing NO₂ should show one blue circle (nitrogen atom) and two red circles (oxygen atoms). NO₂, or nitrogen dioxide, has a bent molecular structure, not triangular, and involves resonance structures.
Step-by-step explanation:
If a blue circle represents one atom of nitrogen, and a red circle represents one atom of oxygen, the picture that represents NO₂ would be the one showing one blue circle and two red circles. The correct representation would be one nitrogen atom (blue circle) bonded to two oxygen atoms (red circles). As per the chemical formula NO₂, which stands for nitrogen dioxide, there is one atom of nitrogen and two atoms of oxygen in the molecule.
The fact that the molecular structure of nitrogen dioxide involves the nitrogen at the center of a triangle seems incorrect, considering nitrogen dioxide is a bent molecule, not a triangular planar molecule. The correct angle around the nitrogen in NO₂ is not 180°; rather, it has a bent shape due to the lone electron on the nitrogen, resulting in a smaller angle between the oxygen atoms.
Additionally, NO₂ has a resonance structure, meaning that the bonding cannot be represented by a single classical chemical structure but is a hybrid of two or more structures.
This requires drawing the nitrogen with one single bond and one double bond to two oxygen atoms, with the position of the double bond shifting between the two oxygens in different resonance structures.