Question

Compare the bond length for NH3, NF3, and PF3. Explain.

Answer 1

The bond length for NH3, NF3, and PF3 can be compared based on their molecular geometry and the strength of the chemical bonds between the atoms.

NH3 has a bond angle of 107 degrees and a bond length of 1.01 Angstroms. This is due to the presence of a lone pair of electrons on the Nitrogen atom which causes the bond angles to deviate from the ideal tetrahedral angles of 109.5 degrees.

NF3 has a bond angle of 107 degrees and a bond length of 1.1 Angstroms. This is due to the presence of a lone pair of electrons on the Nitrogen atom which causes the bond angles to deviate from the ideal tetrahedral angles of 109.5 degrees.

PF3 has a bond angle of about 101 degrees and a bond length of 1.48 Angstroms. This is due to the fact that the Fluorine atoms are larger than the Nitrogen atoms of NH3 and NF3, and the bond between Phosphorus and Fluorine is stronger and shorter than the bond between Nitrogen and Hydrogen or Nitrogen and Fluorine.

In summary, the bond length of NH3 and NF3 is shorter than that of PF3 due to the smaller size of Nitrogen atoms compared to Phosphorus and the presence of lone pairs on Nitrogen atoms. The bond between Nitrogen and Hydrogen or Nitrogen and Fluorine is weaker than the bond between Phosphorus and Fluorine.

Answer 2

The bond lengths in NH3, NF3, and PF3 vary due to the differences in size and electronegativity of the atoms bonded to nitrogen and phosphorus. NF3 has shorter bond lengths compared to PF3 due to the smaller size and higher electronegativity of fluorine compared to phosphorus. NH3 has longer bond lengths than NF3 as hydrogen is less electronegative and larger than fluorine.

Step-by-step explanation:

The bond length comparison for NH3, NF3, and PF3 can be explained by considering the size and electronegativity of the atoms involved. Ammonia (NH3) consists of nitrogen bonded to hydrogen, whereas nitrogen trifluoride (NF3) and phosphorus trifluoride (PF3) have the same central atoms bonded to more electronegative fluorine atoms.

Nitrogen and fluorine have a substantial electronegativity difference, resulting in polar covalent bonds. However, due to fluorine's small size and high electronegativity, the N-F bond in NF3 is shorter than the P-F bond in PF3. This is because phosphorus is a larger atom than nitrogen, leading to a longer bond length with fluorine as they can accommodate more electron density between them.

The bond length in NH3 will generally be longer than in NF3, as hydrogen is less electronegative and a larger atomic radius leads to a longer bond length compared to fluorine. Electronegativity differences in molecules can result in varying bond lengths depending on the atoms involved, with a rough guidance provided in figures that show increasing electronegativity differences leading to more ionic character in the bonds.