Using only the elements P, Br, and Mg, give formulas for the following. (a) An ionic compound

Verified step by step guidance

1. Identify the charges of the ions formed by each element. Phosphorus (P) typically forms a 3- ion (P^3-), bromine (Br) forms a 1- ion (Br^-), and magnesium (Mg) forms a 2+ ion (Mg^2+).
2. Choose a combination of these ions that will result in a neutral compound. The total positive charge must balance the total negative charge.
3. Consider forming a compound with magnesium and bromine, as magnesium can donate electrons to achieve a stable configuration and bromine can accept electrons.
4. Write the formula by balancing the charges. Since Mg has a 2+ charge and Br has a 1- charge, you will need two bromine ions to balance one magnesium ion, resulting in MgBr_2.
5. Verify the neutrality of the compound by ensuring the total positive charge equals the total negative charge. In MgBr_2, the 2+ charge from Mg is balanced by two 1- charges from the two Br ions.

Key Concepts

Ionic Compounds

Ionic compounds are formed when atoms transfer electrons, resulting in the formation of positively charged cations and negatively charged anions. These oppositely charged ions attract each other, creating a stable compound. In this case, magnesium (Mg) can lose two electrons to become Mg²⁺, while phosphorus (P) can gain three electrons to form P³⁻, and bromine (Br) can gain one electron to form Br⁻.

Charge Balance

For an ionic compound to be stable, the total positive charge must balance the total negative charge. This means that the ratio of cations to anions must be such that their charges cancel each other out. For example, to balance Mg²⁺ (2+) with P³⁻ (3-) and Br⁻ (1-), one can combine one Mg²⁺ with two Br⁻ ions to form MgBr₂, or one Mg²⁺ with one P³⁻ and three Br⁻ to form MgPBr₃.

Chemical Formulas

Chemical formulas represent the composition of a compound, indicating the types and numbers of atoms involved. In ionic compounds, the formula reflects the simplest ratio of ions that achieves charge neutrality. For example, the formula MgBr₂ indicates that one magnesium ion pairs with two bromide ions, while MgPBr₃ indicates a combination of one magnesium ion, one phosphide ion, and three bromide ions.