Determine whether each structure is likely to be colored or not. For those that you predict to be colored, indicate the extended conjugation by marking the series of continuous sp² hybridized atoms.
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Verified step by step guidance

1. Step 1: Analyze the structure for conjugation. Conjugation occurs when there is a series of alternating single and double bonds, allowing for delocalization of π-electrons across the molecule. In this structure, observe the aromatic rings and the extended conjugation involving sp2 hybridized atoms.
2. Step 2: Identify the functional groups. The molecule contains a hydroxyl group (-OH) and a nitro group (-NO2). The nitro group is an electron-withdrawing group, which can influence the electronic properties of the conjugated system.
3. Step 3: Determine the extent of conjugation. Mark the series of continuous sp2 hybridized atoms in the aromatic rings and any other conjugated systems. Extended conjugation increases the likelihood of the molecule absorbing visible light and appearing colored.
4. Step 4: Consider the electronic effects of the substituents. The nitro group can pull electron density away from the conjugated system, potentially shifting the absorption spectrum into the visible range. This effect can make the molecule appear colored.
5. Step 5: Predict whether the molecule is likely to be colored. Based on the extended conjugation and the presence of electron-withdrawing groups, the molecule is likely to absorb visible light and exhibit color. Highlight the conjugated system to confirm the prediction.

Key Concepts

Conjugation

Conjugation refers to the overlap of p-orbitals across adjacent sp2 hybridized atoms, allowing for the delocalization of π electrons. This delocalization stabilizes the molecule and can lead to the absorption of visible light, resulting in color. The more extensive the conjugation, the lower the energy gap between the ground and excited states, which can shift the absorption into the visible spectrum.

Hybridization

Hybridization is the concept of mixing atomic orbitals to form new hybrid orbitals that can form sigma bonds. In organic compounds, sp2 hybridization involves one s and two p orbitals, creating three equivalent sp2 orbitals and leaving one p orbital unhybridized. This unhybridized p orbital is crucial for forming π bonds and contributes to the conjugation in colored compounds.

Color and Light Absorption

The color of a compound is determined by the wavelengths of light it absorbs. When a molecule absorbs light, it promotes electrons from a lower energy level to a higher one. If the energy difference corresponds to visible light, the compound will appear colored. The specific wavelengths absorbed depend on the extent of conjugation and the electronic structure of the molecule.