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HOMO LUMO quiz

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  • What does the acronym HOMO stand for in frontier molecular orbital theory?
    HOMO stands for Highest Occupied Molecular Orbital, which is the highest energy orbital containing electrons.
  • What does LUMO represent in molecular orbital theory?
    LUMO stands for Lowest Unoccupied Molecular Orbital, which is the lowest energy orbital that is empty.
  • Why is understanding HOMO and LUMO important in organic chemistry?
    Understanding HOMO and LUMO is foundational for predicting and explaining organic reactions, as frontier orbital interactions drive many reactions.
  • In ethene, which molecular orbital is the HOMO?
    In ethene, the HOMO is the filled pi1 orbital, which contains two electrons.
  • Which orbital in ethene is the LUMO?
    In ethene, the LUMO is the empty pi2* (pi 2 star) orbital.
  • How are molecular orbitals formed in ethene?
    Molecular orbitals in ethene are formed from two atomic orbitals, resulting in a bonding (pi1) and an antibonding (pi2*) orbital.
  • What is the electron configuration principle relevant to filling molecular orbitals in ethene?
    Electrons fill the lowest energy orbital first, so in ethene, the two electrons occupy the pi1 orbital.
  • What happens to the identification of HOMO and LUMO as molecular size increases?
    As molecular size increases and the number of molecular orbitals grows, HOMO and LUMO are found at the boundary between filled and unfilled orbitals.
  • What is the main driving force behind many organic reactions according to frontier molecular orbital theory?
    Frontier orbital interactions, specifically between HOMO and LUMO, are the main driving force behind many organic reactions.
  • How many electrons are in the HOMO of ethene?
    The HOMO of ethene contains two electrons.
  • How many electrons are in the LUMO of ethene?
    The LUMO of ethene contains zero electrons.
  • What is the significance of the pi1 and pi2* orbitals in ethene?
    Pi1 is the bonding orbital filled with electrons (HOMO), and pi2* is the antibonding orbital that is empty (LUMO).
  • What is the relationship between HOMO and LUMO in terms of energy?
    HOMO is the highest energy orbital with electrons, while LUMO is the lowest energy orbital without electrons.
  • What does the 'frontier' in frontier molecular orbital theory refer to?
    The 'frontier' refers to the boundary between the highest filled (HOMO) and lowest unfilled (LUMO) molecular orbitals.
  • Why is the concept of HOMO and LUMO especially important as molecules get larger?
    As molecules get larger, the number of molecular orbitals increases, making it crucial to identify HOMO and LUMO for understanding reactivity.