Molecular Formula Total Number of Valence Electrons Lewis Structure Molecular Geometry SiH4 H20 SO2 CIFs Molecular Formula Total Number of Valence Electrons Lewis Structure Molecular Geometry NH4 XeF4 CO2 NO: H2CO
The Correct Answer and Explanation is :
Let’s analyze the molecular formulas, total number of valence electrons, Lewis structures, and molecular geometries for the specified compounds:
1. SiH₄ (Silane):
- Valence Electrons: Silicon (Si) contributes 4 valence electrons, and each hydrogen (H) contributes 1, totaling 8 valence electrons.- Lewis Structure: Silicon is the central atom bonded to four hydrogen atoms, forming single bonds.- Molecular Geometry: Tetrahedral, with bond angles of approximately 109.5°.
2. H₂O (Water): - Valence Electrons: Oxygen (O) contributes 6 valence electrons, and each hydrogen contributes 1, totaling 8 valence electrons.- Lewis Structure: Oxygen is bonded to two hydrogen atoms with two lone pairs of electrons.- Molecular Geometry: Bent (angular), with a bond angle of approximately 104.5°.
3. SO₂ (Sulfur Dioxide): - Valence Electrons: Sulfur (S) contributes 6 valence electrons, and each oxygen contributes 6, totaling 18 valence electrons.- Lewis Structure: Sulfur is double-bonded to two oxygen atoms, with one lone pair on sulfur and two lone pairs on each oxygen.- Molecular Geometry: Bent, with a bond angle of approximately 120°.
4. ClF₃ (Chlorine Trifluoride): - Valence Electrons: Chlorine (Cl) contributes 7 valence electrons, and each fluorine (F) contributes 7, totaling 26 valence electrons.- Lewis Structure: Chlorine is the central atom bonded to three fluorine atoms, with two lone pairs on chlorine.- Molecular Geometry: T-shaped, with bond angles of approximately 90° and 180°.
5. NH₄⁺ (Ammonium Ion): - Valence Electrons: Nitrogen (N) contributes 5 valence electrons, and each hydrogen contributes 1, totaling 8 valence electrons. The positive charge indicates the loss of one electron, so 7 valence electrons are considered.- Lewis Structure: Nitrogen is the central atom bonded to four hydrogen atoms, with no lone pairs on nitrogen.- Molecular Geometry: Tetrahedral, with bond angles of approximately 109.5°.
6. XeF₄ (Xenon Tetrafluoride): - Valence Electrons: Xenon (Xe) contributes 8 valence electrons, and each fluorine contributes 7, totaling 36 valence electrons.- Lewis Structure: Xenon is the central atom bonded to four fluorine atoms, with two lone pairs on xenon.- Molecular Geometry: Square planar, with bond angles of 90° and 180°.
7. CO₂ (Carbon Dioxide): - Valence Electrons: Carbon (C) contributes 4 valence electrons, and each oxygen contributes 6, totaling 16 valence electrons.- Lewis Structure: Carbon is double-bonded to two oxygen atoms, with no lone pairs on carbon and two lone pairs on each oxygen.- Molecular Geometry: Linear, with a bond angle of 180°.
8. NO (Nitric Oxide): - Valence Electrons: Nitrogen (N) contributes 5 valence electrons, and oxygen (O) contributes 6, totaling 11 valence electrons.- Lewis Structure: Nitrogen is double-bonded to oxygen, with one lone pair on nitrogen and one lone pair on oxygen.- Molecular Geometry: Linear, with a bond angle of 180°.
9. H₂CO (Formaldehyde): - Valence Electrons: Carbon (C) contributes 4 valence electrons, oxygen (O) contributes 6, and each hydrogen contributes 1, totaling 12 valence electrons.- Lewis Structure: Carbon is double-bonded to oxygen and single-bonded to two hydrogen atoms.- Molecular Geometry: Trigonal planar, with bond angles of approximately 120°.
Explanation:
The molecular geometry of a compound is determined by the Valence Shell Electron Pair Repulsion (VSEPR) theory, which posits that electron pairs around a central atom arrange themselves to minimize repulsion. This theory helps predict the three-dimensional shapes of molecules based on the number of bonding and non-bonding electron pairs.
- Tetrahedral Geometry: ccurs when a central atom is bonded to four atoms with no lone pairs, as seen in SiH₄ and NH₄⁺.- Bent Geometry: esults from two bonding pairs and one or two lone pairs on the central atom, leading to a non-linear shape, as observed in H₂O and SO₂.- T-shaped Geometry: rises when there are three bonding pairs and two lone pairs on the central atom, as in ClF₃.- Square Planar Geometry: ccurs when there are four bonding pairs and two lone pairs on the central atom, as in XeF₄.- Linear Geometry: ound in molecules with two bonding pairs and no lone pairs on the central atom, such as CO₂ and NO.- Trigonal Planar Geometry: esults from three bonding pairs and no lone pairs on the central atom, as in H₂CO.
Understanding these geometries is crucial for predicting the physical and chemical properties of molecules, including polarity, reactivity, and interaction with other substances.