Barrons SAT Subject Test Chemistry, 13th Edition

(Marvins-Underground-K-12) #1

  1. (A) The ground state is the lowest-energy, or most stable state, of an
    atom. The lithium atom has 3 electrons. In its stable state, the 1s sublevel, or
    lowest-energy orbital, contains a pair of electrons. The Pauli Exclusion
    Principle allows a maximum of 2 electrons with opposite spins, so the third
    electron resides in the 2s orbital.

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