Which statement is FALSE regarding the Lewis structure for XeF4?
A The formal charge on the central atom is not zero.
B A total of 36 valence electrons are represented.
C The central atom has lone-pair electrons.
D It includes only single bonds.
The correct answer and explanation is :
The FALSE statement regarding the Lewis structure for XeF4 is:
D. It includes only single bonds.
Explanation:
To understand why option D is false, let’s break down the Lewis structure for xenon tetrafluoride (XeF4):
- XeF4 and its Electron Configuration:
Xenon (Xe) is a noble gas in group 18, so it has 8 valence electrons. Fluorine (F) is a halogen, and each fluorine atom has 7 valence electrons. XeF4 consists of one xenon atom and four fluorine atoms, so the total number of valence electrons is:
- Xe: 8 electrons
- 4 × F: 4 × 7 = 28 electrons
- Total = 8 + 28 = 36 valence electrons.
- Bonds in the Lewis Structure:
The four fluorine atoms form single bonds with the xenon atom, as fluorine typically forms a single bond with other atoms (due to its 7 valence electrons, which leaves it needing only one more electron to complete its octet). This satisfies the bonding requirements for each fluorine atom. - Lone Pairs and Formal Charges:
After forming the single bonds, 32 electrons are used (4 bonds × 2 electrons per bond), leaving 4 electrons, which are placed as lone pairs on the xenon atom. Xenon, being in period 5, can accommodate more than 8 electrons in its valence shell, and it does so in this case. This gives xenon 2 lone pairs. - Formal Charges:
The formal charge on the xenon atom in XeF4 is not zero. Calculating formal charge on xenon involves comparing the number of valence electrons (8) with the number of electrons it “owns” in the Lewis structure. In XeF4, xenon is surrounded by 4 bonding pairs and 2 lone pairs. The resulting formal charge on xenon is typically +2, which is nonzero.
Why is D False?
Option D suggests that XeF4 contains only single bonds, but this is misleading because while each fluorine forms a single bond with xenon, XeF4 includes lone pairs on xenon, not only single bonds. This is a more nuanced feature of the structure and is essential for its correct representation.
In summary, D is false because the statement oversimplifies the structure, ignoring the presence of lone pairs on xenon.