Decide if the molecule has a dipole moment, (if the molecule is
polar) as follows:
a) dipole (polar molecule)
b) no dipole (non-polar molecule)
c) ionic (not a molecule)
d) super covalent
e) none of the above
11.) CsF
12.) nitrogen
13.) Methane
14.) ammonia
15.) CH3F
To determine if a molecule has a dipole moment (is polar) or not (non-polar), you need to consider the molecule's molecular geometry and the polarity of its bonds.
1) CsF:
- Cesium (Cs) is a metal, and fluorine (F) is a non-metal. CsF has an ionic bond because of the large difference in electronegativity between Cs and F. Therefore, it is categorized as "ionic" and not a molecule. The answer is c) ionic (not a molecule).
2) Nitrogen (N):
- Nitrogen (N) exists as diatomic nitrogen gas (N₂) in its elemental form, and it contains a nonpolar covalent bond. Since it has a linear molecular geometry with symmetrically distributed electrons, the molecule has no net dipole moment. The answer is b) no dipole (non-polar molecule).
3) Methane (CH₄):
- Methane (CH₄) has a tetrahedral molecular geometry due to the four identical C-H bonds. Although the C-H bonds are polar, the molecule is nonpolar because the bond dipoles cancel each other out symmetrically. The answer is b) no dipole (non-polar molecule).
4) Ammonia (NH₃):
- Ammonia (NH₃) has a trigonal pyramidal molecular geometry with three hydrogen atoms surrounding a central nitrogen atom. The N-H bonds are polar, and the molecule has a lone pair of electrons on the nitrogen atom. As a result, the molecule has a net dipole moment. The answer is a) dipole (polar molecule).
5) CH₃F:
- CH₃F is a molecule containing a central carbon atom bonded to three hydrogen atoms and one fluorine atom. The molecular geometry is tetrahedral, and the C-F bond is polar due to the electronegativity difference. However, since the molecule is not symmetric, the bond polarities do not cancel each other out, resulting in a net dipole moment. The answer is a) dipole (polar molecule).
By considering the molecular geometry and the polarity of the individual bonds, you can determine whether a molecule has a dipole moment or not.
To determine if a molecule has a dipole moment (polar) or not (non-polar), we need to consider the difference in electronegativity between the atoms and the molecular geometry.
1. CsF (Cesium Fluoride):
- Cs is a metal and F is a non-metal, so it is an ionic compound rather than a molecule. Therefore, the answer is c) ionic.
2. Nitrogen (N2):
- Nitrogen is a diatomic molecule consisting of two nitrogen atoms. The electronegativity of nitrogen is the same for both atoms, so there is no difference in electronegativity. Additionally, the molecular geometry of N2 is linear.
- As a result, the molecule N2 is non-polar, and the answer is b) no dipole.
3. Methane (CH4):
- Methane is a tetrahedral molecule with the carbon atom at the center and four hydrogen atoms surrounding it. The electronegativity difference between carbon and hydrogen is minimal.
- Due to the symmetric arrangement of the four C-H bonds, the vector sum of all the dipole moments cancels out, resulting in a non-polar molecule. Hence, the answer is b) no dipole.
4. Ammonia (NH3):
- Ammonia has a pyramidal molecular geometry, with the nitrogen atom at the top and three hydrogen atoms forming a triangular base. Nitrogen is more electronegative than hydrogen, resulting in a polar covalent bond.
- The dipole moments of the N-H bonds do not cancel each other out due to the asymmetrical shape, resulting in a net dipole moment. Thus, the molecule NH3 is polar, and the answer is a) dipole.
5. CH3F (Methyl fluoride):
- CH3F has a tetrahedral molecular geometry, similar to methane. Fluorine is more electronegative than carbon and hydrogen.
- The dipole moments of the C-F bonds do not cancel out due to the asymmetry of the molecule. Therefore, CH3F has a net dipole moment and is polar. The answer is a) dipole.
To summarize:
11.) CsF: c) ionic
12.) Nitrogen: b) no dipole
13.) Methane: b) no dipole
14.) Ammonia: a) dipole
15.) CH3F: a) dipole