Answer
See the explanation
Work Step by Step
1. Drawing the Lewis structures for the given compounds and ions:
$PF_{5}$ (Phosphorus Pentafluoride):
The Lewis structure for $PF_{5}$ shows that the central phosphorus atom has 10 electrons around it, which is an exception to the octet rule.
$SF_{4}$ (Sulfur Tetrafluoride):
The Lewis structure for $SF_{4}$ shows that the central sulfur atom has 10 electrons around it, which is an exception to the octet rule.
$ClF_{3}$ (Chlorine Trifluoride):
The Lewis structure for $ClF_{3}$ shows that the central chlorine atom has 10 electrons around it, which is an exception to the octet rule.
$Br_{3}^{-}$ (Tribromide Ion):
The Lewis structure for $Br_{3}^{-}$ shows that the central bromine atom has 10 electrons around it, which is an exception to the octet rule.
2. Elements that can have more than eight electrons around them:
The elements that can have more than eight electrons around them are the elements in the third period and beyond (from the third row of the periodic table onwards), such as phosphorus (P), sulfur (S), chlorine (Cl), and bromine (Br).
3. Rationalization:
The ability of these elements to have more than eight electrons around them is due to the presence of d-orbitals in their valence shell. The d-orbitals can accommodate additional electrons, allowing these elements to exceed the octet rule and form compounds or ions with more than eight electrons around the central atom.
This is known as "expanded octet" or "hypervalent" bonding, and it is a result of the increased number of available orbitals in the valence shell of these elements. The d-orbitals can participate in bonding, leading to the formation of compounds or ions with more than eight electrons around the central atom.
