Predict the chemical formula for the ionic compound formed by (e) Mg2+ and PO43-.

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Identify the charges on the ions: Mg^{2+} has a charge of +2 and PO_4^{3-} has a charge of -3.

To form a neutral compound, the total positive charge must balance the total negative charge.

Determine the least common multiple (LCM) of the charges: The LCM of 2 and 3 is 6.

Calculate the number of each ion needed to achieve charge balance: You need 3 Mg^{2+} ions (3 x +2 = +6) and 2 PO_4^{3-} ions (2 x -3 = -6).

Write the chemical formula by placing the number of each ion as subscripts: Mg_3(PO_4)_2.

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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 atoms transfer electrons, resulting in the formation of charged ions. These compounds typically consist of a metal cation and a non-metal anion. The electrostatic attraction between the oppositely charged ions leads to the formation of a stable ionic lattice structure.

Charge Balance

In ionic compounds, the total positive charge from cations must balance the total negative charge from anions to achieve electrical neutrality. This requires determining the ratio of cations to anions based on their respective charges. For example, if a cation has a +2 charge and an anion has a -3 charge, the formula must reflect a combination that results in a net charge of zero.

Chemical Formula Representation

The chemical formula of an ionic compound indicates the types and ratios of ions present. It is written by combining the symbols of the constituent ions, with subscripts denoting the number of each ion needed to achieve charge balance. For example, the formula for magnesium phosphate, formed from Mg2+ and PO43-, is determined by finding the lowest whole number ratio that balances the charges.

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