IV. There is one more policy that helps the hotel run smoothly and keep customers happy. Hund's Rule states that if electrons are being placed in the same section of a floor (rooms that cost the same) then each one gets their own room and has the same spin until the floor is half-filled. If any more electrons want to stay in that same section, then they must pair up with another electron and assume the opposite spin. This does not necessarily apply to electrons that have purchased more expensive rooms. In the diagrams below identify the areas in which Hund's Rule was broken. Describe how the rule is being broken in each case. 1 1111| 11 ||1 11L 1L 1L 1L 1L February 12, 1997 November 26, 1995 July 10, 1983 C V. OBSERVATIONS: A. How many "rooms" are there in an "s" suite of a floor? B. How many "rooms" are there in a "p" suite of a floor? C. How many "rooms" are there in a "d" suite of a floor? D. How many electrons can stay on the first floor? second floor? third floor? E. Describe how the rooms in each section are numbered. F. In diagram C (Section IV above), describe why the electron could go into the 4s orbital instead of the 3p. G. Why might section 3d fall between section 4s and 4p?

Which of the following statements is FALSE? An orbital that penetrates into the region occupied by core electrons is more shielded from nuclear charge than an orbital that does not penetrate and therefore has a lower energy. Two electrons in the same orbital cannot have the same spin. An orbital that penetrates into the region occupied by core electrons is less shielded from nuclear charge than an orbital that does not penetrate and therefore has a lower energy. None of the above is false. It is not possible for two electrons in the same atom to have identical values for all four quantum numbers.

8. Hund's rule states that a) in the same orbital only 2 electron of opposite spin are possible b) we cannot know the exact position of an electron c) the p orbital must always be filled before the s orbital d) each electron tends to occupy an empty orbital before occupying an orbital which contains another electron 9. Which of the following sets of quantum numbers are impossible? Explain your choice a) (1,0, 0, -½) d) (4,3,-2, +½) b) (3,0,1, +½) e) (3,2,1,1) c) (2,2,1, +½)

6. Using Slater's rules, calculate the Zeff on one of the 3d electrons compared to that on one of the 4s electrons for Mn. 7. Using Slater's rules, calculate the Zef on a 3p electron in Al and in Cl. Explain how your results relate to a. the relative atomic radii of the two atoms. b. the relative first ionization energies of the two atoms.