Consider the molecules pictured. Which molecules have a formal charge of zero on the central atom? CIF3 BF3 XeF, SiF 4 all O only XeF4 O only CIF3 none
Formal Charges
Formal charges have an important role in organic chemistry since this concept helps us to know whether an atom in a molecule is neutral/bears a positive or negative charge. Even if some molecules are neutral, the atoms within that molecule need not be neutral atoms.
Polarity Of Water
In simple chemical terms, polarity refers to the separation of charges in a chemical species leading into formation of two polar ends which are positively charged end and negatively charged end. Polarity in any molecule occurs due to the differences in the electronegativities of the bonded atoms. Water, as we all know has two hydrogen atoms bonded to an oxygen atom. As oxygen is more electronegative than hydrogen thus, there exists polarity in the bonds which is why water is known as a polar solvent.
Valence Bond Theory Vbt
Valence bond theory (VBT) in simple terms explains how individual atomic orbitals with an unpaired electron each, come close to each other and overlap to form a molecular orbital giving a covalent bond. It gives a quantum mechanical approach to the formation of covalent bonds with the help of wavefunctions using attractive and repulsive energies when two atoms are brought from infinity to their internuclear distance.
![### Formal Charge Calculation of Central Atoms in Molecules
Consider the molecules pictured. Which molecules have a formal charge of zero on the central atom?
**Molecules:**
- ClF₃
- BF₃
- XeF₄
- SiF₄
**Options:**
1. All
2. Only XeF₄
3. Only ClF₃
4. None
To determine the correct answer, we need to calculate the formal charge of the central atom in each molecule. The formal charge (FC) is calculated using the formula:
\[ \text{FC} = \text{Valence Electrons} - (\text{Lone Pair Electrons} + \frac{1}{2} \times \text{Bonding Electrons}) \]
Below are the steps to determine the formal charge for the central atom in each molecule:
1. **ClF₃:**
- Chlorine (Cl) has 7 valence electrons.
- ClF₃ has three single bonds with fluorine atoms.
- Two lone pairs of electrons are on chlorine.
\[ \text{FC} = 7 - (2 + \frac{1}{2} \times 6) \]
\[ \text{FC} = 7 - (2 + 3) = 7 - 5 = 2 \]
The formal charge on Cl is not zero.
2. **BF₃:**
- Boron (B) has 3 valence electrons.
- BF₃ has three single bonds with fluorine atoms and no lone pairs.
\[ \text{FC} = 3 - (0 + \frac{1}{2} \times 6) \]
\[ \text{FC} = 3 - 3 = 0 \]
The formal charge on B is zero.
3. **XeF₄:**
- Xenon (Xe) has 8 valence electrons.
- XeF₄ has four single bonds with fluorine atoms and two lone pairs.
\[ \text{FC} = 8 - (4 + \frac{1}{2} \times 8) \]
\[ \text{FC} = 8 - (4 + 4) = 8 - 8 = 0 \]
The formal charge on](/v2/_next/image?url=https%3A%2F%2Fcontent.bartleby.com%2Fqna-images%2Fquestion%2Fe87c8d2c-f5b5-44c8-ba3f-4d81f60a2fcf%2F9249019a-5907-4eff-bbea-df7ac60098a8%2Ff8ddkws.jpeg&w=3840&q=75)
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