Unformatted text preview: -energy antibonding orbitals ( ! * p ) , so they should have electrons that are easier to
remove as compared to N2, which has no ! * p electrons. To differentiate which has the easiest
! * p to remove, concentrate on the number of electrons in the orbitals attracted to the number
of protons in the nucleus.
N22− and N2− both have 14 protons in the two nuclei combined. Because N22− has more
electrons, one would expect N22− to have more electron repulsions, which translates into
having an easier electron to remove. Between O2 and O2+, the electron in O2 should be easier CHAP. 14
595 COVALENT BONDING: ORBITALS - EVEN-NUMBER PROBLEMS to remove. O2 has one more electron than O2+, and one would expect the fewer electrons in
O2+ to be better attracted to the nuclei (and harder to remove). Between N22− and O2, both
have 16 electrons; the difference is the number of protons in the nucleus. Because N22− has 78
two fewer protons than O2, one would expect the N22− to have the easiest electron to remove
which translates into the smallest ionization energy. 80. 2p 2s O2 O2− O2 + O The order from lowest IE to highest IE is: O2− < O2 < O2+ < O.
The electrons for O2−, O2 , and O2 + that are highest in energy are in the ! * p MOs. But for O2−,
these electrons are paired. O2− should have the lowest ionization energy (its paired ! * p
electron is easiest to remove). The species O2+ has an overall positive charge, making it
harder to remove an electron from O2+ than from O2. The highest energy electrons for O (in
the 2p atomic orbitals) are lower in energy than the ! * p electrons for the other species; O will
have the highest ionization energy because it requires a larger quantity of energy to remove
an electron from O as compared to the other species. CHAP. 14
596 82. COVALENT BONDING: ORBITALS - EVEN-NUMBER PROBLEMS The molecular orbitals for BeH2 are formed from the two hydrogen 1s orbitals and the 2s and
one of the 2p orbitals from beryllium. One of the sigma bonding orbitals forms from overlap
of the hydrogen 1s o...
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