Types of Chemical Bonds
What type of bond is formed when electrons are shared equally between two atoms?
What is a nonpolar covalent bond?
What type of intermolecular force is present in all molecules, regardless of polarity?
What are London dispersion forces?
What is the general structure of an ionic solid, and how does it relate to its properties?
Ionic solids form a regular lattice structure, which contributes to their high melting points and brittleness.
What does a Lewis structure represent, and what information does it convey about a molecule?
A Lewis structure represents the arrangement of valence electrons in a molecule and shows how atoms are bonded.
What does VSEPR theory stand for, and how does it help predict molecular shape?
VSEPR stands for Valence Shell Electron Pair Repulsion; it predicts molecular shape based on the repulsion between electron pairs around a central atom.
What type of bond results from the complete transfer of electrons from one atom to another?
What is an ionic bond?
Describe how hydrogen bonds affect the boiling point of water compared to other similar-sized molecules.
Hydrogen bonds significantly increase the boiling point of water, making it higher than that of similar-sized molecules, due to strong attractions between water molecules.
What are two key properties of metals that arise from metallic bonding?
Metals are good conductors of electricity and are malleable.
Draw the Lewis structure for CO₂ and identify the type of bonds present.
The Lewis structure shows a central carbon atom double-bonded to two oxygen atoms, indicating two double bonds.
Describe the hybridization of the central atom in a molecule with a tetrahedral shape. Provide an example.
The hybridization is sp³, as in the case of CH₄ (methane), which has four equivalent bonds to hydrogen atoms.
Describe the main characteristics of metallic bonds and their impact on the properties of metals.
Metallic bonds involve a "sea of electrons" that allows metals to conduct electricity and heat and gives them their malleability and ductility.
Compare dipole-dipole interactions with London dispersion forces in terms of strength and examples of substances that exhibit each.
Dipole-dipole interactions are stronger than London dispersion forces and occur in polar molecules, while London dispersion forces occur in all molecules but are particularly significant in nonpolar ones.
How does the arrangement of atoms in alloys affect their strength compared to pure metals?
The presence of different-sized atoms in alloys disrupts the regular atomic arrangement, making them stronger and harder than pure metals.
Calculate the formal charge of the central atom in the molecule H₂O.
The formal charge on the oxygen in H₂O is 0, while the hydrogen atoms each have a formal charge of 0.
For a molecule with the formula AB₃, identify its molecular geometry and the hybridization of the central atom.
The geometry is trigonal planar, and the central atom is sp² hybridized.
What are the differences in properties between ionic and covalent compounds in terms of melting point and solubility in water?
Ionic compounds generally have higher melting points and are soluble in water, while covalent compounds typically have lower melting points and may not dissolve in water.
Explain how the strength of intermolecular forces influences the viscosity of a liquid.
Stronger intermolecular forces result in higher viscosity because they create greater resistance to flow as molecules stick together more tightly.
Describe how the ionic radius affects the stability and properties of ionic compounds.
Smaller ionic radii lead to stronger ionic bonds due to closer packing and greater electrostatic attraction, resulting in higher melting points.
Explain how resonance structures contribute to the overall stability of a molecule. Draw two resonance structures for the nitrate ion (NO₃⁻).
Resonance structures show different arrangements of electrons; for NO₃⁻, the structures involve one double bond to one oxygen and single bonds to the other two, leading to delocalized electrons and increased stability.
How does the presence of lone pairs affect the bond angles in a molecule? Provide an example.
Lone pairs repel more strongly than bonding pairs, reducing bond angles; for example, in H₂O, the bond angle is about 104.5° instead of 109.5° due to the presence of two lone pairs on oxygen.
Explain how electronegativity affects bond formation and polarity in molecules.
Electronegativity determines how electrons are shared in a bond; greater differences in electronegativity lead to polar covalent or ionic bonds, while similar values lead to nonpolar covalent bonds.
Analyze how potential energy changes as two polar molecules come closer together and the implications for their interaction.
As polar molecules approach each other, their potential energy decreases due to attractive dipole-dipole interactions, which stabilizes the system and can lead to an overall release of energy.
What is the difference between substitutional and interstitial alloys?
Substitutional alloys have atoms of similar sizes replacing each other in the lattice, while interstitial alloys have smaller atoms fitting into the spaces between larger atoms in the lattice.
Discuss the importance of formal charge in determining the preferred Lewis structure for a molecule. Use ozone (O₃) as an example.
The preferred Lewis structure minimizes formal charges; for ozone, the structure with the least formal charge on each atom is favored, showing resonance between two structures.
Explain how the hybridization and molecular geometry of the molecule NH₃ differ from that of CH₄.
NH₃ is sp³ hybridized with a trigonal pyramidal geometry due to one lone pair, leading to bond angles of about 107°, while CH₄ is also sp³ hybridized but has a tetrahedral geometry with bond angles of 109.5°.