Which of the following is a polar molecule ? [NEET 2013]a)SF4b)SiF4c)XeF4d)BF3Correct answer is option 'A'. Can you explain this answer?

Question

Answer

Sif4 n BF3 has regular shape so the resulant dipole moment equals zero...

XeF4 has 4bondpair n 2 lone pair and SP3d2 hybridisation. ...and square planer structure...where the bond dipoles cancel each other..
so resultant dipole moment equals zero..

in SF4 4bp n 1 lp present with Sp3d hybridisation...it has seasaw shape which is irregular....so resultant dipole moment not equal to zero...

hence SF4 is a polar molecule

Answer

Two of the S-F bonds are pointing away from each other, and their bond dipoles cancel. But the other two S-F dipoles are pointing 'down'. Their bond dipoles do not cancel, so the molecule is polar.

Answer

Explanation:

Polarity of a molecule depends on the presence of polar bonds and the overall molecular geometry.

Step 1: Determine the Lewis structure
First, we need to determine the Lewis structure of each molecule to identify the polar bonds.

- SF4: In SF4, sulfur (S) has 6 valence electrons, and each fluorine (F) atom contributes 7 valence electrons. The total number of valence electrons is 34. The Lewis structure of SF4 will have one sulfur atom in the center and four fluorine atoms surrounding it. Sulfur will form single bonds with each fluorine atom and will have one lone pair of electrons. The Lewis structure for SF4 is:

F
|
F-S-F
|
F

- SiF4: In SiF4, silicon (Si) has 4 valence electrons, and each fluorine (F) atom contributes 7 valence electrons. The total number of valence electrons is 32. The Lewis structure of SiF4 will have one silicon atom in the center and four fluorine atoms surrounding it. Silicon will form single bonds with each fluorine atom. The Lewis structure for SiF4 is:

F
|
F-Si-F
|
F

- XeF4: In XeF4, xenon (Xe) has 8 valence electrons, and each fluorine (F) atom contributes 7 valence electrons. The total number of valence electrons is 42. The Lewis structure of XeF4 will have one xenon atom in the center and four fluorine atoms surrounding it. Xenon will form single bonds with each fluorine atom and will have two lone pairs of electrons. The Lewis structure for XeF4 is:

F
|
F-Xe-F
|
F

- BF3: In BF3, boron (B) has 3 valence electrons, and each fluorine (F) atom contributes 7 valence electrons. The total number of valence electrons is 24. The Lewis structure of BF3 will have one boron atom in the center and three fluorine atoms surrounding it. Boron will form single bonds with each fluorine atom. The Lewis structure for BF3 is:

F
|
F-B-F
|
F

Step 2: Determine the polarity of each molecule
To determine the polarity of each molecule, we need to consider both the polar bonds and the overall molecular geometry.

- SF4: In SF4, the sulfur-fluorine bonds are polar due to the difference in electronegativity between sulfur and fluorine. Additionally, the molecule has a trigonal bipyramidal molecular geometry. The lone pair of electrons on sulfur creates a region of electron density that distorts the molecular shape, resulting in an overall polar molecule.
- SiF4: In SiF4, the silicon-fluorine bonds are polar due to the difference in electronegativity between silicon and fluorine. However, the molecule has a tetrahedral molecular geometry, which results in the polarities of the bonds canceling out. Therefore, SiF4 is a nonpolar molecule.
- XeF4: In XeF4, the xenon-fluorine

Top Courses for Class 12View all

English Class 12

Chemistry Class 12

Physics Class 12

English Flamingo Class 12

Physical Education Class 12(XII) - Notes & Model Test Papers

Top Courses for Class 12

Top Courses for Class 12

Related Content

Schools

Competitive Examinations

Quick Access Links

Technical Exams