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Lewis Formulas and octet rule

I am having trouble understanding these questions and would appreciate if you could please help me and show whatever work to better help me understand.

Please refer to the attachment for original questions:

1. A step in determining Lewis formulas of covalent species is to find the total number of electrons that are used in the formula. Find such totals for the following:
A. CS2
B. PCl3
C. CCl4
D. NO3- E. CH4
Note: This question says to give just the numbers of electrons. It does not require writing of the Lewis formulas.

2. An atom of a particular element has a mass of 24.312amu(atomic mass units).
An amu is 1.6605x10-24 grams. What is the mass of this atom
A. in grams?
B. in kilograms.

3. Explain how the octet rule applies to
A. The ionic compound KBr
B. The covalent molecule Cl2

4. A. How does an Al atom become an Al3+ ion ?
B. How does a S atom become a S2- ion ?

5. A substance sample contains 1.522 grams of N and 3.478g of O. Another sample contains 1.826g of N and 4.173g of O. Are these the same compound. Show how you arrive at your answer.

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Solution Summary

In the solution, detailed explanation is provide for counting the valence electrons in the compounds. Meanwhile, for other questions, detailed tutorial is presented for converted amu to kg or g. Finally, octet rule is used to explain both ionic compound and other molecules.

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