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Water and Molecular Bonds in General Biology

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이 집합의 용어 (20)

  • What type of bond shares electrons equally between atoms?
    Nonpolar covalent bonds share electrons equally, such as in C-C or C-H bonds.
  • What makes a covalent bond polar?
    Polar covalent bonds share electrons unequally due to differences in electronegativity, e.g., O-H bonds.
  • Why is water (H2O) a polar molecule?
    Water is polar because oxygen is more electronegative than hydrogen, causing electrons to spend more time near oxygen, creating partial charges.
  • What is the shape and bond angle of a water molecule?
    Water has a bent molecular shape with a bond angle of about \(104.4^\circ\) due to lone pairs on oxygen.
  • How does molecular shape affect polarity?
    Asymmetrical shapes like water create polarity, while symmetrical shapes like methane (CH4) are nonpolar.
  • What is electronegativity and its role in bond polarity?
    Electronegativity is an atom's ability to attract electrons; differences cause polar covalent bonds.
  • What is a hydrogen bond?
    A hydrogen bond is a weak attraction between a partially positive hydrogen and a partially negative atom like oxygen or nitrogen.
  • Are electrons shared in hydrogen bonds?
    No, hydrogen bonds are noncovalent and do not involve electron sharing.
  • Why are hydrogen bonds important in biology?
    They stabilize structures like DNA double helix and protein folding, and contribute to water's unique properties.
  • What are emergent properties of water due to hydrogen bonding?
    Cohesion, adhesion, high specific heat, ice floating, and solvent abilities.
  • What does hydrophilic mean?
    Hydrophilic molecules are polar and interact well with water.
  • What does hydrophobic mean?
    Hydrophobic molecules are nonpolar and do not dissolve in water.
  • How does water moderate temperature changes?
    Water's high specific heat allows it to absorb heat with little temperature change, stabilizing environments.
  • Why does ice float on water?
    Ice is less dense because stable hydrogen bonds form a crystal lattice that spaces molecules apart.
  • What is the pH scale a measure of?
    The pH scale measures the concentration of hydrogen ions \([H^+]\) in a solution.
  • How is pH calculated?
    pH = \(-\log_{10}[H^+]\), a logarithmic scale.
  • What is the pH of pure water and why?
    Pure water has a neutral pH of 7 because \([H^+] = [OH^-]\).
  • What is the difference between acids and bases in terms of H+ ions?
    Acids donate H+ ions and lower pH; bases accept H+ ions and raise pH.
  • What role do buffers play in biological systems?
    Buffers resist changes in pH by absorbing or releasing H+ ions.
  • How do ionic compounds like salt dissolve in water?
    Water molecules surround ions, with oxygen attracting cations and hydrogen attracting anions, separating them.