Question

consider structures h, j, k:
what structure has an expanded octet?

Explanation:

An expanded octet occurs when an atom has more than eight electrons in its valence shell. This is typically seen in elements from the third period and below in the periodic table as they have access to \(d\) - orbitals.

• For structure \(j\) (\(OPF_3\)), the central \(P\) (phosphorus, period 3) atom:
• The \(P\) atom has a double - bond with \(O\) and single - bonds with three \(F\) atoms. Using the formula for the number of valence electrons around an atom (\(V=\text{number of bonds}+\text{number of lone pairs}\times2\)), for \(P\), the number of bonds is \(4\) (one double - bond and three single - bonds, equivalent to 4 electron - pair bonds) and if we consider formal charge and electron - pair distribution, the total number of valence electrons around \(P\) is more than 8.
• For structure \(n\) (\(PF_5\)), the central \(P\) atom:
• \(P\) forms five single - bonds with \(F\) atoms. Using the formula \(V=\text{number of bonds}+\text{number of lone pairs}\times2\), with \(5\) single - bonds (and assuming no lone pairs on \(P\) for a simple Lewis - structure consideration of the expanded octet case), the number of valence electrons around \(P\) is \(10\) (since each single - bond has 2 electrons).

Answer:

j, n