Molecules 273
b r
b
(b)
+
(a)
r
a
a
Contours of
electron probability
+
(c)
b r
a
A
R
+ +
b r
(d)
a
A
R
+ +
(e)
r
R = 0
He+(2p)
2+
Figure 8.6 (a)–(d) The combination of two hydrogen-atom 1swave functions to form the antisymmetric
H 2 wave function A. A stable H 2 molecular ion is not formed because now the electron has a smaller
probability of being between the protons than outside them. (e) If the protons could join together,
the resulting wave function would be the same as the 2pwave function of a Heion. In the 2pstate
a Heion has more energy than in the 2sstate.
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