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The Correct Answer and Explanation is:
. H2O (Water)
- Electron-dot formula: H-O-H
- Oxygen is the central atom with two lone pairs and two bonds to hydrogen atoms.
- Shape: Bent or V-shaped
- The lone pairs on oxygen cause a repulsion that leads to a bent shape, with an angle of about 104.5°.
- Explanation: Oxygen has six valence electrons and forms two bonds with two hydrogen atoms, leaving two lone pairs on oxygen. The repulsion between the lone pairs and bonding pairs causes the bent shape. Water is polar due to its asymmetrical distribution of charge.
2. SF2 (Sulfur Difluoride)
- Electron-dot formula: F-S-F
- Sulfur is the central atom with two single bonds to fluorine atoms, and two lone pairs on sulfur.
- Shape: Bent
- Similar to water, the lone pairs on sulfur create repulsion, resulting in a bent shape with a bond angle of approximately 98°.
- Explanation: Sulfur in SF2 has six valence electrons, two of which form bonds with fluorine atoms. The remaining four electrons are lone pairs. The bent shape arises from the repulsion between the lone pairs and bonding pairs, making the molecule polar.
3. NI3 (Nitrogen Triiodide)
- Electron-dot formula: I-N-I
- Nitrogen is the central atom with three single bonds to iodine atoms, and one lone pair on nitrogen.
- Shape: Trigonal pyramidal
- The lone pair on nitrogen causes repulsion that pushes the iodine atoms slightly downward from the ideal 120° angle, resulting in a trigonal pyramidal shape.
- Explanation: Nitrogen has five valence electrons, three of which bond with iodine atoms. The lone pair on nitrogen contributes to the trigonal pyramidal shape, which makes the molecule polar.
4. SiBr4 (Silicon Tetrabromide)
- Electron-dot formula: Br-Si-Br
- Silicon is the central atom with four single bonds to bromine atoms and no lone pairs.
- Shape: Tetrahedral
- The bonding pairs of electrons are arranged symmetrically around silicon, creating a tetrahedral shape with a bond angle of 109.5°.
- Explanation: Silicon has four valence electrons, all used in bonding with bromine atoms. Since there are no lone pairs, the molecule adopts a symmetric tetrahedral shape, making it nonpolar.
5. SO3 (Sulfur Trioxide)
- Electron-dot formula: O=S=O
- Sulfur is the central atom with double bonds to three oxygen atoms and no lone pairs on sulfur.
- Shape: Trigonal planar
- The bonding pairs are arranged symmetrically around sulfur, resulting in a trigonal planar shape with 120° bond angles.
- Explanation: Sulfur in SO3 has six valence electrons, all involved in double bonds with oxygen atoms. The lack of lone pairs and the symmetry of the molecule result in a trigonal planar shape, and since the charge distribution is symmetric, the molecule is nonpolar.
6. CO2 (Carbon Dioxide)
- Electron-dot formula: O=C=O
- Carbon is the central atom with double bonds to two oxygen atoms, and no lone pairs on carbon.
- Shape: Linear
- The bonding pairs of electrons are arranged symmetrically around carbon, resulting in a linear shape with a bond angle of 180°.
- Explanation: Carbon has four valence electrons, two of which form double bonds with oxygen atoms. Since there are no lone pairs on the carbon atom, the molecule adopts a linear shape. This symmetry makes CO2 nonpolar, despite the polar bonds.
Summary of Molecular Shapes:
- H2O: Bent
- SF2: Bent
- NI3: Trigonal pyramidal
- SiBr4: Tetrahedral
- SO3: Trigonal planar
- CO2: Linear
Each molecule’s shape is influenced by the number of bonds and lone pairs on the central atom, with the Valence Shell Electron Pair Repulsion (VSEPR) theory helping us predict these shapes based on electron pair repulsion.
