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Re: Chemistry problem, again



I object on principle to giving students homework answers. The fact that
the question is related to the periodic table should be a sufficient hint.
I will, however, utter the magic words, "closed shells".


On Sun, 12 Oct 2003, Herbert H Gottlieb wrote:

I posted this problem here a few days ago, but no replies
have been received yet.. Please help!


One of my grandsons, Everett, was given the following
problem in his high school chemistry class today
Any help that you can give will be greatly appreciated.

Herb Gottlieb

-------------- ---------------- ------------------

Everett writes....

Below is the prompt and the following questions. I really only need some
guidance with the structure of the periodic table. Otherwise my only
question concerns number 6 about oxidating numbers. How does that work?
Any help would be greatly appreciated. Thanks!


You are an astronaut who lands on an imaginary planet in hyperspace where
only 40 elements exist. After studying some spectroscopic data and doing
some wave-mechanical calculations, you determine that the electrons in
the atom’s occupy 5 principal energy levels labeled: 1, 2, 3, 4, and 5.
Level 1 can contain 2 electrons. Level 2 can contain 6 electrons. Levels
3, 4, and 5 can contain 12 electrons each. Each level can have one or
more sublevels labeled: a, b, and c. Sublevel a contains 1 orbital.
Sublevel b contains a set of 2 orbital. Sublevel c contains a set of 3
orbital. Each orbital can contain a maximum of 2 electrons.

The order of filling the sublevels is as follows:

1a, 2a, 2b, 3a, 3c, 3b, 4a, 4c, 4b, 5a, 5c, 5b

1. Set up a periodic table of your 40 elements in order of increasing
numbers of electrons and based strictly on electron configuration. Use
the symbol for the highest occupied sublevel to designate the element.
For example, the element containing only one electron would be designated
as 1a 1 since it has one electron in the 1a sublevel. The element
containing 3 electron would be designated as 2a1 since it contains one
electron in the 2a sublevel, the highest occupied sublevel.

2. Reorganize these elements in a period way and add the rest of the
elements.

3. Assign each element in your periodic table an atomic number in the
upper left hand corner of its box to indicate its total number of
electrons.

4. Write out the complete electron configuration of element 4b3 .

5. How many “undiscovered” elements might there be room for in your
periodic chart?

6. Predict the oxidation numbers of elements 22, 18, 3, 31, and 5.

7. Element 1a2 has a completely full principal energy level. Based on
your prediction of its chemical properties, where might you alternatively
place 1a2 in your periodic table? Explain.

8. Predict some chemical properties of elements 3b4 and 4a1

9. Assuming the laws of physics and chemistry are the same in hyperspace
as on earth, draw arrows to show probable increasing trends in:

a) ionization energy
b) atomic radius
c) metallic properties

10. Label the groups in your periodic table:

a) hyperspace alkali metals
b) alkaline hyperspace metals
c) hyperspace transition metals
d) hyperspace noble gases
e) hyperspace non-metals


--
"Don't push the river, it flows by itself"
Frederick Perls