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Solved: Use Lewis symbols to determine the formula for the
Chapter 9, Problem 42E(choose chapter or problem)
Problem 42E
Use Lewis symbols to determine the formula for the compound that forms between each pair of elements:
a. Ca and N
b. Mg and I
c. Ca and S
d. Cs and F
Questions & Answers
QUESTION:
Problem 42E
Use Lewis symbols to determine the formula for the compound that forms between each pair of elements:
a. Ca and N
b. Mg and I
c. Ca and S
d. Cs and F
ANSWER:
Solution 42 E Step 1 of 4 Couple a) Calcium (Ca) belongs to II A group, thus it has two electrons in its outer shell Nitrogen (N) belongs to V A group thus it has five electrons in its outer shell. Because of the Nitrogen’s high electronegativity respect to Calcium, Nitrogen can gain two electrons from Calcium. In order to reach their stability, Calcium can give two electrons to Nitrogen, but Nitrogen needs only three electrons to complete its outer shell. So we have to think in a different way respect to other times. If we look to the picture above, we can see that Calcium has two unpaired electrons, while Nitrogen has three unpaired electrons. So the better is to consider that the atoms mix together in a reverse ratio respect to their unpaired electrons. In this case, since the ratio between the Calcium’s unpaired electrons and Nitrogen unpaired electrons is 2:3, we need to combine Ca end N in a 3:2 ratio, thus obtaining the formula Ca O . 3 2 Calcium turns to be a positive, bivalent, ion (because every atom of Calcium loses two electrons) Nitrogen becomes a negative, trivalent ion (because every atom of Nitrogen acquires two electrons). Thus the Lewis formula for the final compound is the one we see as a product of the reaction below