Questions and Answers
Compare and contrast covalent, polar covalent, ionic and metallic bonding.
All four are chemical bonds between atoms. Covalent and polar covalent involve the sharing of electrons, but polar covalent is an uneven sharing. Ionic bonding occurs when electrons are transferred from one atom to another, and metallic bonding is when electrons are shared throughout a network of atoms in a large pool.
Why are only the valence electrons drawn when drawing Lewis structures?
Valence electrons are the outermost electrons and they are the only ones involved in bonding.
What is the octet rule and what are common exceptions to it?
The octet rule states that most atoms are most stable with 8 electrons in the valence shell. Common exceptions are hydrogen, helium, boron, and beryllium.
Compare single, double, and triple bonds in terms of the amount of electrons involved, the length of the bond, and the strength of the bond.
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An unknown compound dissolves in water but does not conduct electricity. What type of bond is it most likely to be?
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What type of bond is NaBr?
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What type of bond is CH4?
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What type of bond is SO2?
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What type of bond is NH3?
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What type of bond is MgO?
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What type of bond is H2O?
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What's the difference between intermolecular and intramolecular forces?
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How do intermolecular forces affect melting and boiling points?
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What are viscosity and surface tension, and how does the strength of the intermolecular forces affect these two properties?
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What type of forces must be overcome to vaporize (boil off) a substance? Are these forces intramolecular or intermolecular?
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Explain why ethyl alcohol (C2H5OH) has a higher boiling point (78.4C) than methyl alcohol (CH3OH) whose boiling point is 64.7C.
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Briefly define and explain hydrogen bonds, then rank it in terms of strength.
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Briefly define and explain dipole-dipole forces, then rank it in terms of strength.
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Briefly define and explain London dispersion forces, then rank it in terms of strength.
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Study Notes
Bonding Types
- Covalent Bonding: Involves sharing of electrons between two nonmetal atoms; can be non-polar (equal sharing) or polar (uneven sharing).
- Ionic Bonding: Occurs through transfer of electrons from metals to non-metals, resulting in electrostatic attraction.
- Metallic Bonding: Features a "sea of electrons" shared among a lattice of metal atoms.
Lewis Structures
- Only valence electrons are depicted as they are involved in chemical bonding.
- Valence electrons are the outermost electrons of an atom.
Octet Rule
- Atoms typically seek to have 8 electrons in their valence shell to achieve stability.
- Common exceptions include hydrogen (2 electrons), helium (2), boron (6), and beryllium (4).
Types of Bonds
- Single Bonds: Involve 2 electrons; longer and weaker compared to double and triple bonds.
- Double Bonds: Comprise 4 electrons; shorter and stronger than single bonds.
- Triple Bonds: Consist of 6 electrons; the shortest and strongest type of bond.
Bond Type Identification
- NaBr: Ionic
- CH4: Covalent
- SO2: Covalent
- NH3: Ionic
- MgO: Ionic
- H2O: Covalent
Forces in Molecules
- Intermolecular Forces: Attractions occurring between separate molecules.
- Intramolecular Forces: Attractions within a single molecule, including chemical bonds.
Impact of Intermolecular Forces
- Stronger intermolecular forces increase melting and boiling points, as more energy is needed to break them.
- Viscosity: The resistance to flow; higher intermolecular forces result in higher viscosity.
- Surface Tension: The ability of a liquid's surface to resist an external force; stronger intermolecular forces lead to higher surface tension.
Boiling and Vaporization
- To vaporize a substance, intermolecular forces must be overcome, not intramolecular forces.
Boiling Point Comparison
- Ethyl alcohol (C2H5OH) has a boiling point of 78.4°C, higher than methyl alcohol (CH3OH) at 64.7°C, due to increased molecular mass leading to stronger intermolecular forces.
Types of Intermolecular Forces
- Hydrogen Bonding: Strongest type of intermolecular force, significant in molecules containing hydrogen bonded to electronegative atoms (N, O, F).
- Dipole-Dipole Forces: Intermediate strength forces occurring between polar molecules due to their dipole moments.
- London Dispersion Forces: Weakest intermolecular forces arising from temporary shifts in electron density in non-polar molecules.
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Description
Prepare for your chemistry final with these flashcards focusing on different types of chemical bonds: covalent, polar covalent, ionic, and metallic. Understand how each bonding type operates and how they differ from one another in terms of electron sharing and transfer. Mastering these concepts will enhance your grasp of chemical interactions.
