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Chemical Bonds and Mixtures in Anatomy & Physiology

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Termini in questo insieme (20)

  • What are the three basic types of mixtures?
    Solutions, colloids, and suspensions.
  • Define a solution in terms of mixtures.
    A homogeneous mixture with particles evenly distributed; solvent is the substance in greatest amount, solutes are dissolved substances.
  • What characterizes a colloid?
    A heterogeneous mixture with larger particles than solutions that scatter light but do not settle out; can undergo sol-gel transformations.
  • Describe a suspension.
    A heterogeneous mixture with very large particles that settle out over time, such as blood cells settling in plasma.
  • List three main differences between mixtures and compounds.
    Mixtures do not involve chemical bonding, can be separated physically, and can be heterogeneous or homogeneous; compounds involve chemical bonds, separated chemically, and are homogeneous.
  • What is the role of electrons in chemical bonding?
    Electrons in the outermost shell (valence shell) determine chemical reactions and bond formation by gaining, losing, or sharing electrons.
  • What is the octet rule?
    Atoms tend to have 8 electrons in their valence shell to achieve stability, except hydrogen and helium which are stable with 2 electrons.
  • What makes an element chemically inert?
    Having a full valence shell of electrons, making it stable and nonreactive, like noble gases.
  • Define ionic bonds.
    Chemical bonds formed by the transfer of valence electrons from one atom to another, creating oppositely charged ions that attract.
  • What happens when sodium and chlorine form an ionic bond?
    Sodium transfers its valence electron to chlorine, forming a Na+ cation and a Cl- anion, which attract to form sodium chloride.
  • How are covalent bonds formed?
    By sharing pairs of valence electrons between atoms; can be single, double, or triple bonds depending on the number of shared electron pairs.
  • What distinguishes polar covalent bonds from nonpolar covalent bonds?
    Polar covalent bonds have unequal sharing of electrons causing partial charges; nonpolar covalent bonds share electrons equally.
  • Give an example of a polar molecule and explain why it is polar.
    Water (H2O) is polar because oxygen is more electronegative, pulling electrons closer and creating partial negative and positive charges.
  • What is a hydrogen bond?
    A weak attraction between a partially positive hydrogen atom of one molecule and a partially negative electronegative atom of another.
  • Compare the relative strengths of covalent, ionic, and hydrogen bonds.
    Covalent bonds are strongest, ionic bonds are intermediate, and hydrogen bonds are weakest.
  • What is the significance of hydrogen bonding in water?
    Hydrogen bonds give water its polarity, high surface tension, and ability to form cohesive interactions important for biological functions.
  • What are van der Waals interactions?
    Weak attractions due to asymmetrical electron distribution creating temporary positive and negative regions that allow molecules to stick together.
  • What is the valence shell and why is it important?
    The outermost electron shell of an atom; electrons here have the most potential energy and participate in chemical bonding.
  • How many electrons can the first three electron shells hold?
    Shell 1 holds up to 2 electrons, shell 2 up to 8, and shell 3 up to 18 electrons.
  • Why do atoms form chemical bonds?
    To achieve a full valence shell of electrons, usually 8, which provides chemical stability.