What are the formulas of the compounds formed from the following ions? (a) Ca 2+ and Br - (b) Ca 2+ and SO 4 2- (c) Al 3+ and SO 4 2-

Welcome back everyone. We need to give the resulting chemical formulas when the following ions combined. So looking at part one, we have our magnesium two plus catty on combining with the chloride an ion. So we're going to recognize that magnesium based on its position on the periodic table being in Group two. A So it's a group to a medal. Whereas chloride or chlorine we recognize on the product table is considered a non metal based on its position when we have the combination of a metal and a nonmetal, we form an ionic compound meaning we have a transfer of electron charge or of electrons. And so when these ions combine, we're going to form our magnesium with the charge of chlorine which will have a subscript of one that is implied. And chlorine which will now carry the charge of magnesium as a subscript of two. This would be our first answer as our chemical formula for the resulting combined ions. Moving on to Part Two, we have again are magnesium two plus caddy on combining with this time a poly atomic ion Because we have multiple atoms phosphorus bonded to four atoms of oxygen with a -3 charge. We want to recognize that this poly atomic ion is known as phosphate. So this is a poly atomic ion which is ultimately just an ion being bonded to our metal ion of magnesium. So this should be yet again another ionic compound. We have the transfer of electrons and we would form our magnesium with the charge of our phosphate, which is a subscript of three now And our phosphate poly atomic ion will be in parentheses P 04 where it's now going to carry the charge of our magnesium caddy on as a subscript of two. This would be our second answer. And now moving on to part three, we have our galleon. Catalon recognized that on our periodic table we find gallium in group three A which is why it makes sense to have a three plus Catalan charge as an ion. And now we have again, phosphate are poly atomic ion with a minus three charge. And so because again this is the combination of gallium which is a group three A metal based on its position with a poly atomic ion, we have an ionic compound where we have gallium which is going to carry the charge of our phosphate. But because our three missing electrons from phosphate are transferred to gallium, that's going to cancel out gallium three plus Catalan charge, meaning that gallium was missing. These three electrons recall that when we have a positive charge we lose electrons. When we have a negative charge we gain electrons. So galleon gains these three electrons from phosphate and phosphate loses its three electrons from transferring them to gallium, meaning that our formula is just going to be G. A P 04 because the three plus and three minus will cancel each other out. And so We can note down that are charges canceled. So plus three and -3 cancel. And so therefore our third and final answer is G A p. 04 as our chemical formula when these ions combined in Part three. So everything highlighted in yellow represents our final answer. I hope everything I reviewed was clear. If you have any questions, leave them down below, and I will see everyone in the next practice video.

Ch.2 - Atoms, Molecules & Ions

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McMurry 8th Edition

Ch.2 - Atoms, Molecules & Ions

Problem 154

Chapter 2, Problem 154

What are the formulas of the compounds formed from the following ions? (a) Ca²⁺ and Br^- (b) Ca²⁺ and SO₄^2- (c) Al³⁺ and SO₄^2-

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Identify the charges on each ion: Ca^{2+}, Br^{-}, SO_4^{2-}, and Al^{3+}.

For each pair of ions, balance the total positive and negative charges to ensure the compound is neutral.

For (a) Ca^{2+} and Br^{-}, determine how many Br^{-} ions are needed to balance the charge of one Ca^{2+} ion.

For (b) Ca^{2+} and SO_4^{2-}, check if the charges are already balanced or if any adjustments are needed.

For (c) Al^{3+} and SO_4^{2-}, find the smallest number of each ion needed to balance the charges, using the least common multiple if necessary.

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Key Concepts

Here are the essential concepts you must grasp in order to answer the question correctly.

Ionic Compounds

Ionic compounds are formed when cations (positively charged ions) and anions (negatively charged ions) combine. The overall charge of the compound must be neutral, meaning the total positive charge from cations must balance the total negative charge from anions. Understanding how to combine these ions based on their charges is essential for determining the correct formulas of the resulting compounds.

Charge Balance

Charge balance is a fundamental principle in chemistry that dictates how ions combine to form neutral compounds. For example, a Ca2+ ion has a +2 charge, while a Br- ion has a -1 charge. To achieve neutrality, two Br- ions are needed to balance one Ca2+ ion, resulting in the formula CaBr2.

Polyatomic Ions

Polyatomic ions are ions composed of two or more atoms that are covalently bonded and carry a net charge. For instance, the sulfate ion (SO42-) has a -2 charge. When combining polyatomic ions with cations, it is crucial to consider the overall charge of the polyatomic ion to ensure the final compound is electrically neutral, as seen in the formation of CaSO4 and Al2(SO4)3.