Homework Solutions

January 8

68.    Cu: [Ar]4s²3d⁹ although it may be [Ar]4s¹3d¹⁰
        O 1s²2s²2p⁴
        La:  [Xe]6s²5d¹
        Y:  [Kr]5s²4d¹
        Ba:  [Xe]6s²
        Tl:  [Xe]6s²6p¹
        Bi:  [Xe]6s²6p³

72.    a.  As:  [Ar]4s²4p³
        b.  [Rn]7s²7p⁴
        c.  Ta:  [Xe]6s²5d³
        d.  At:  [Xe]6s²6p⁵

73.    What do we mean when we say that a 4s electron is more penetrating than a 3d electron?  We mean that the 4s electron is able to penetrate the shielding of the 1s, 2s, 2p, 3s, and 3p electrons in order to be close to the nucleus.  This is because the 4s orbital has density near the nucleus, inside the other orbitals.