CHEMISTRY 131Quiz #5 Friday, February 24, 2006Name: _____________Key_____________________ 1. Briefly explain why Ca+2is found in nature, while Ca+is not. Do not use the phrase "stable octet" in your answer, and do not personify atoms ("likes", "wants", "prefers", etc.) (4 points) In order to form each type of ion, electrons must be removed from the 4s orbital of Ca. Thus, there is not really any difference in the effective nuclear charge that is involved during the formation of Ca+and Ca+2. The reason that Ca+2is found in nature is simply that Ca+2makes salts that are more energetically stable than those containing Ca+. When ions of opposite charge are brought together to form a solid, ions with higher charges release more potential energy than those with lower charges; for example, a +2/-1 interaction is more energetically stable than a +1/-1 interaction. 2. Sphalerite and rock salt are both 1:1 structure types. When a +1 ion and a –1 ion are combined to form a solid, what feature of the ions controls whether one solid or the other will be formed? (2 points)
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