Molecular Shapes and VSEPR Theory

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Questions and Answers

What is the molecular shape and formula of ammonia?

The molecular shape of ammonia is trigonal pyramidal and its formula is NH3.

Describe the molecular shape and formula for water (H2O).

Water has a bent or angular shape and its formula is H2O.

Identify the molecular shape and the chemical identity of cisplatin.

Cisplatin has a square planar shape and its chemical identity is cis-PtCl2(NH3)2.

What is the geometry of sulfur hexafluoride (SF6)?

Sulfur hexafluoride has an octahedral geometry. Signup and view all the answers

What type of molecular shape is represented by AB2E2 and give an example.

AB2E2 represents a bent or angular shape, with water (H2O) as an example. Signup and view all the answers

How does the presence of lone pairs influence molecular shape?

Lone pairs repel more strongly than bond pairs, altering the bonds' angles and creating different shapes. Signup and view all the answers

Provide the bond angles commonly associated with a trigonal pyramidal molecular shape.

Trigonal pyramidal molecular shapes generally have bond angles of approximately 107 degrees. Signup and view all the answers

What is the significance of the molecular shape being square planar in cisplatin?

The square planar shape in cisplatin is crucial for its biological activity as a chemotherapeutic agent. Signup and view all the answers

What effect does SF6's octahedral shape have on its physical properties?

SF6's octahedral shape contributes to its properties such as being colorless, odorless, and non-flammable. Signup and view all the answers

Explain the molecular shape of a substance with the general formula AB4E2.

AB4E2 gives a square planar shape, with the central atom surrounded by four bonding pairs and two lone pairs. Signup and view all the answers

What is the coordination number of the ferrous hexaaqua ion, Fe(H2O)6²⁺?

6 Signup and view all the answers

What are the expected bond angles in CH4 according to VSEPR theory?

109.5° Signup and view all the answers

How does the angle of SO3²⁻ compare to that of CH4, and what is its actual angle?

SO3²⁻ has a smaller angle of 106° due to the presence of lone pairs. Signup and view all the answers

In VSEPR theory, which type of repulsion is considered to be the strongest?

Lone/lone pair repulsions Signup and view all the answers

What role does sulfur hexafluoride (SF6) play in ultrasound imaging?

SF6 enhances the echogenicity of blood, improving the signal to noise ratio. Signup and view all the answers

What is the significance of treating multiple bonds as single bonds in VSEPR theory?

It simplifies the geometry predictions by avoiding issues with resonance structures. Signup and view all the answers

Identify the molecular shape and coordination number for SF6.

The molecular shape is octahedral with a coordination number of 6. Signup and view all the answers

Why is it energetically more favorable for lone pairs to be as far from one another as possible?

To minimize repulsion between negatively charged lone pairs. Signup and view all the answers

What is the significance of EDTA in metal ion chelation?

EDTA acts as a chelating agent, binding divalent transition metal ions like Fe2+. Signup and view all the answers

What is the structural formula for ferrous sulfate in the presence of water?

FeSO4 · xH2O Signup and view all the answers

What is the actual bond angle in water (H2O) as per VSEPR theory?

104.5° Signup and view all the answers

Describe the structural feature of the complex formed when FeSO4 dissolves in water.

An octahedral complex is formed with water molecules coordinating to Fe2+ ions. Signup and view all the answers

How does the octahedral shape of an EDTA-metal complex influence its stability?

The octahedral shape allows for optimal spatial arrangement, enhancing the complex's stability. Signup and view all the answers

Discuss the implications of lone pair repulsions on the geometry of ammonia (NH3).

The presence of a lone pair compresses the bond angles, making them approximately 107°. Signup and view all the answers

What causes the differences in bond angles between SO3²⁻ and CH4?

The lone pairs in SO3²⁻ create greater repulsion, reducing the bond angle from the tetrahedral angle. Signup and view all the answers

What is the chemical formula of disodium edetate?

The chemical formula is Na2EDTA. Signup and view all the answers

What type of complex does EDTA form with metal ions?

EDTA forms octahedral complexes with divalent metal ions. Signup and view all the answers

Explain the significance of the molecular shape AB6.

The molecular shape AB6 indicates a central atom (A) bonded to six peripheral atoms (B), forming an octahedral arrangement. Signup and view all the answers

What implications does the echogenicity of blood have for medical imaging?

Increased echogenicity improves the clarity and accuracy of ultrasound images. Signup and view all the answers

How does the formation of an octahedral complex affect the solubility of FeSO4?

The formation of an octahedral complex increases the solubility of FeSO4 in water. Signup and view all the answers

Study Notes

Molecular Shape

AB3E (Trigonal Pyramidal): Ammonia (NH3) has a trigonal pyramidal shape with three hydrogen atoms bonded to a central nitrogen atom and one lone pair of electrons
AB2E2 (Bent, Angular, V-shaped): Water (H2O) has a bent shape due to two lone pairs and two bonding pairs of electrons around the central oxygen atom. The lone pairs repel the bonding pairs causing a smaller angle.
AB4E2 (Square Planar): Cisplatin (cis-PtCl2(NH3)2) is a square planar molecule with two chlorine atoms, two ammonia molecules bonded to a platinum atom in a square planar configuration. It is used as an anticancer drug.
AB6 (Octahedral): Sulfur hexafluoride (SF6) is a colorless, odorless, non-flammable gas used in ultrasound imaging. It has six fluorine atoms surrounding a central sulfur atom in an octahedral shape.

VSEPR Theory

Predicting Molecular Shape: VSEPR theory is used to predict the three-dimensional shape of molecules by taking into account the repulsion between valence electron pairs in a molecule.
Lone Pair Repulsions: Lone pairs of electrons repel each other more strongly than bonding pairs.
Multiple Bonds: Treat multiple bonds as single bonds for simplicity when using VSEPR theory.
Examples: The bond angle in methane (CH4) is 109.5°, while the bond angle in sulfite (SO32-) is 106° because of the lone pairs on the sulfur atom.

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Description

This quiz explores different molecular shapes including trigonal pyramidal, bent, square planar, and octahedral configurations. It also covers VSEPR theory, which helps predict the 3D arrangement of atoms in a molecule. Test your understanding of molecular geometry and its applications in chemistry.