17. Why, in terms of electron probability clouds, are two electrons in the orbital forced close to one another, whereas an electron in a or orbital are farther apart? Why does this lead to the prediction that all three p orbitals will be occupied with one electron each before any one of them receives a second electron?

18. What orbitals are being filled across the representative elements in the periodic table? What orbitals are associated with the transition metals? With the inner transition metals?

19. What are two alternative names for the first series of inner transition metals? What is another name for the second series of inner transition metals?

20. Why, based on electronic configurations, will elements in the same vertical column of the periodic table tend to have similar chemical properties?

21. What is common to the electronic structures of all of the noble gases? How does this contribute to their chemical behavior?

22. What is the big-bang theory of the origin of the universe, and how does it differ from the steady-state theory? Which is more likely to be correct, according to what we know now?