Final answer:
The central atoms in HCN, O₂, NO₃⁻, and CO₂ exhibit different hybridizations. Carbon in HCN is sp hybridized, the oxygen atoms in O₂ are unhybridized, nitrogen in NO₃⁻ is sp² hybridized, and carbon in CO₂ is also sp hybridized.
Step-by-step explanation:
The hybridization of the central atom in molecules or ions is determined by the number of electron pairs around the central atom, including both bonding pairs and lone pairs. Here, we will identify the hybridization of the central atoms for certain compounds that contain multiple bonds.
- HCN: In hydrogen cyanide, the carbon atom is the central atom and is triple-bonded to nitrogen and singly bonded to hydrogen. This results in two sigma (σ) bonds and no lone pairs on the carbon, leading to sp hybridization.
- O₂: Oxygen (O₂) has a double bond between the two oxygen atoms. Each oxygen atom has a total of three lone pairs and one sigma (σ) bond, which results in a simple molecular orbital arrangement that does not require hybridization; thus, the orbitals remain unhybridized p orbitals.
- NO₃⁻: In the nitrate ion (NO₃⁻), the nitrogen atom is surrounded by three equivalent oxygen atoms in a trigonal planar arrangement with sp² hybridization to accommodate three sigma (σ) bonds and a delocalized pi (π) bonding system over the three N-O bonds.
- CO₂: In carbon dioxide, the carbon atom is the central atom double-bonded to two oxygen atoms, with two sigma (σ) bonds and two pi (π) bonds. The central carbon atom with no lone pairs is sp hybridized.