LS7A Week 1 Flashcards
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Questions and Answers

What is a polar covalent bond?

A polar covalent bond is characterized by unequal sharing of electrons.

What is a nonpolar covalent bond?

A covalent bond between atoms that have the same or nearly the same electronegativity, sharing the bonding electron pair almost equally.

A polar covalent bond is due to:

  • Equal sharing of valence electrons.
  • The interaction between an ion and a non-ionic atom.
  • Unequal sharing of electrons in a covalent bond. (correct)
  • An attraction of opposite charges.
  • The dash (—) in the structural formula for hydrogen gas (H2) represents a(n):

    <p>Chemical bond.</p> Signup and view all the answers

    A molecule of common table salt (NaCl) is the result of what type of bond?

    <p>An ionic bond.</p> Signup and view all the answers

    Why does the salt dissolve in water?

    <p>The partial positive charges on hydrogen atoms in water molecules are attracted to chlorine ions, and the partial negative charges on oxygen atoms in water molecules are attracted to sodium ions.</p> Signup and view all the answers

    What is a hydrogen bond?

    <p>An interaction between a hydrogen atom and an electronegative atom.</p> Signup and view all the answers

    What kind of bond joins hydrogen to oxygen in a water molecule?

    <p>Polar covalent bond.</p> Signup and view all the answers

    The hydrogen atoms in a water molecule have a ________ charge while the oxygen atom has a _________ charge.

    <p>partial positive; partial negative</p> Signup and view all the answers

    In an ice crystal, how many other water molecules does a single water molecule typically form hydrogen bonds with?

    <p>4</p> Signup and view all the answers

    Which atom is least likely to participate in hydrogen bonds with water?

    <p>Carbon</p> Signup and view all the answers

    What is necessary for a hydrogen atom in a molecule to participate in a hydrogen bond?

    <p>It must be bonded to a more electronegative atom.</p> Signup and view all the answers

    Why does ice float?

    <p>The crystal lattice forces a less dense arrangement of molecules.</p> Signup and view all the answers

    PH is a measure of the concentration of _______ in solution.

    <p>protons</p> Signup and view all the answers

    The unique properties of water are due to the _____ of water molecules and the ability of water to form _____ with other water molecules.

    <p>Polarity; hydrogen bonds.</p> Signup and view all the answers

    Water can dissolve many compounds due to which fact?

    <p>The fact that water molecules are polar.</p> Signup and view all the answers

    Water is neither hydrophilic nor hydrophobic, because these terms only define the interaction of other molecules with water molecules.

    <p>False</p> Signup and view all the answers

    Which of the statements is true regarding a polar molecule?

    <p>A polar molecule is hydrophilic and will dissolve in water.</p> Signup and view all the answers

    How many hydrogen atoms does a molecule with three carbon atoms linked by single covalent bonds contain?

    <p>8</p> Signup and view all the answers

    How many hydrogen atoms are present in a hydrocarbon chain of five carbon atoms with two double bonds and two single bonds?

    <p>8</p> Signup and view all the answers

    Study Notes

    Chemical Bonds

    • Polar Covalent Bond: Involves unequal sharing of electrons between atoms, leading to a partial charge difference.
    • Nonpolar Covalent Bond: Occurs between atoms with similar electronegativity, resulting in nearly equal sharing of electrons.

    Ionic Bonds

    • Example: Sodium chloride (NaCl) results from an ionic bond between sodium (Na) and chlorine (Cl) atoms.
    • Sodium ions attract partial negative charges from oxygen in water, while chlorine ions attract partial positive charges from hydrogen in water.

    Water Molecule Properties

    • Polar Covalent Bond in Water: The bond between hydrogen and oxygen in water molecules is polar, resulting in a partial positive charge on hydrogen atoms and a partial negative charge on the oxygen atom.
    • Hydrogen Bonds: Weaker interactions between a hydrogen atom and an electronegative atom, contributing to water's unique properties.

    Ice and Density

    • Ice floats due to the crystal lattice structure formed during freezing, which creates a less dense arrangement of water molecules.

    pH and Protons

    • pH refers to the concentration of protons (H⁺) in solution, influencing acidity and basicity.

    Properties of Water

    • The unique properties of water arise from the polarity of water molecules and their ability to form hydrogen bonds with other water molecules and polar substances.
    • Water's polarity allows it to dissolve numerous compounds, making it an effective solvent.

    Molecular Interactions

    • Hydrophilic vs. Hydrophobic: Water is not strictly hydrophilic (water-attracting) or hydrophobic (water-repelling); these terms describe how different substances interact with water.
    • Polar molecules are hydrophilic and typically dissolve in water, while nonpolar molecules are hydrophobic and do not.

    Hydrocarbon Structures

    • In a hydrocarbon chain with three carbon atoms bound in a V shape, each unshared electron can bond with hydrogen, resulting in a total of eight hydrogen atoms for the molecule.
    • For a hydrocarbon chain with five carbon atoms, two double bonds, and two single bonds, there are also eight hydrogen atoms present.

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    Test your knowledge with these flashcards on polar and nonpolar covalent bonds. Learn how unequal sharing of electrons defines these chemical bonds, and understand their properties with concise definitions. A great way to prepare for the upcoming LS7A assessments!

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