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General Biology: Atoms, Molecules, and Chemical Bonds

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Termini in questo insieme (20)

  • What determines the chemical reactivity of an atom?
    The electrons in the outermost or valence shell determine an atom's chemical reactivity.
  • What is the maximum number of electrons in the first three electron shells?
    Shell 1 holds up to 2 electrons, Shell 2 up to 8 electrons, and Shell 3 up to 8 electrons.
  • What makes an atom stable?
    An atom is stable when its valence shell is full: 2 electrons in shell 1, 8 in shell 2, and 8 in shell 3.
  • What defines an element?
    The atomic number, which is the number of protons in the nucleus, defines an element.
  • What is the relationship between protons and electrons in a neutral atom?
    In a neutral atom, the number of protons equals the number of electrons.
  • What is the octet rule?
    Atoms tend to gain, lose, or share electrons to have 8 electrons in their valence shell for stability.
  • How do atoms with incomplete outer shells achieve stability?
    They interact by sharing, donating, or receiving electrons to complete their valence shells, forming chemical bonds.
  • What are ionic bonds?
    Ionic bonds form between ions with full positive or negative charges due to electron transfer.
  • What are covalent bonds?
    Covalent bonds form when atoms share outer electrons; they can be polar or nonpolar.
  • What is the difference between polar and nonpolar covalent bonds?
    Polar covalent bonds share electrons unequally, creating partial charges; nonpolar share electrons equally.
  • What is electronegativity?
    Electronegativity is an atom's ability to attract shared electrons in a bond.
  • Which atoms are highly electronegative?
    Oxygen and nitrogen are highly electronegative atoms.
  • What is a hydrogen bond?
    A hydrogen bond is a weak attraction between a partially positive hydrogen atom and a partially negative atom like oxygen or nitrogen.
  • Are electrons shared in hydrogen bonds?
    No, electrons are not shared in hydrogen bonds; they are noncovalent interactions.
  • What is the significance of hydrogen bonds in biology?
    Hydrogen bonds contribute to the structure and function of DNA, proteins, and the unique properties of water.
  • What is the chemical formula of glucose and what does it indicate?
    Glucose is C6H12O6, indicating 6 carbon atoms, 12 hydrogen atoms, and 6 oxygen atoms.
  • What is the atomic mass unit (AMU) of protons, neutrons, and electrons?
    Protons and neutrons have an AMU of 1; electrons have an AMU of 0.
  • What is the charge of protons, neutrons, and electrons?
    Protons are +1, neutrons are neutral (0), and electrons are -1.
  • How is the pH scale related to hydrogen ion concentration?
    pH = -log10[H+]; a one-unit change in pH represents a tenfold change in hydrogen ion concentration.
  • What is the pH of pure water and why?
    Pure water has a neutral pH of 7 because [H+] equals [OH-] at 10^-7 M.