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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, achieving stability.
  • How do atoms with incomplete outer shells achieve stability?
    They interact by sharing, donating, or receiving electrons, forming chemical bonds.
  • What are the two main types of chemical bonds?
    Ionic bonds (transfer of electrons) and covalent bonds (sharing of electrons).
  • What is an ionic bond?
    A bond formed by the attraction between oppositely charged ions after electron transfer.
  • What is a covalent bond?
    A bond formed by the sharing of valence electrons between atoms.
  • What is the difference between polar and nonpolar covalent bonds?
    Polar covalent bonds have unequal sharing of electrons causing partial charges; nonpolar bonds share electrons equally.
  • What is electronegativity?
    The ability of an atom to attract shared electrons in a covalent bond.
  • Which atoms are highly electronegative?
    Oxygen and Nitrogen are highly electronegative atoms.
  • How is polarity indicated in polar covalent bonds?
    Partial positive and negative charges are denoted by δ+ and δ- on bonded atoms.
  • What is the typical number of bonds formed by Carbon, Nitrogen, Oxygen, and Hydrogen?
    Carbon forms 4 bonds, Nitrogen 3, Oxygen 2, and Hydrogen 1.
  • What is a redox reaction?
    A chemical reaction involving electron transfer: oxidation (loss) and reduction (gain) of electrons.
  • How do you determine the type of bond between two atoms?
    Calculate the difference in electronegativity; large difference (>1.7) indicates ionic, smaller difference indicates covalent.
  • What type of bond is found in hydrochloric acid (HCl) with electronegativities H=2.1 and Cl=3.0?
    Polar covalent bond, because the electronegativity difference is 0.9.
  • What is the structure of a water molecule (H2O)?
    Two hydrogen atoms covalently bonded to one oxygen atom, forming a polar molecule.
  • What is the significance of chemical bonds in biology?
    Chemical bonds form molecules that determine the structure and function of biomolecules.