On the basis of the expected charges on the monatomic ions, give the chemical formula of each of the following compounds: (a) gallium arsenide; (b) magnesium oxide; (c) ahuminum telluride; (d) ruthenium(IV) oxide; (c) vanadium(V) oxide.

Understanding monatomic ion charges is foundational in chemistry, especially when it comes to predicting and writing chemical formulas of compounds. Monatomic ions are atoms that have lost or gained electrons, acquiring a charge in the process. These charges are typically determined by the element's group on the periodic table, with metals often forming positive ions (cations) and non-metals forming negative ions (anions). For example, gallium (Ga) from group 13 tends to lose three electrons and becomes a Ga^3+ cation, while arsenic (As) from group 15 tends to gain three electrons, thus becoming an As^3- anion.

Recognizing the common charge for an element allows students to pair ions together to form neutral compounds, an essential step in predicting the chemical formulas of compounds. Our textbook exercise demonstrated this with gallium arsenide (GaAs), where gallium and arsenic ions combine in a 1:1 ratio to offset their charges and create a stable compound.

Writing chemical formulas involves not only recognizing the charges on monatomic ions but also the skill of combining these ions in the correct ratio to achieve charge neutrality. The principle of charge neutrality states that the total positive charge in a compound must balance the total negative charge. This is well illustrated in our example where magnesium oxide (MgO) forms by combining one magnesium cation (Mg^2+) with one oxide anion (O^2-).

However, the challenge arises when dealing with ions of different charges, such as in aluminum telluride (Al2Te3). Students must remember that the charge on each ion type controls the ratio in which ions combine. In this case, two aluminum ions (each with a +3 charge) are needed to balance three telluride ions (each with a -2 charge), hence the formula Al2Te3. The guided steps provided in the textbook solutions are crucial in helping students visualize how to reach these ratios.

Compound nomenclature is the system used to name chemical compounds. The nomenclature for ionic compounds includes the cation name followed by the anion name. For transition metals, their varying charges are indicated using Roman numerals in parentheses. This is why we see 'ruthenium(IV) oxide' for RuO2, where the (IV) indicates the +4 charge of ruthenium. Meanwhile, if an element forms only one type of ion (like magnesium or aluminum), no charge is specified in the name.

The nomenclature becomes crucial for communicating the composition of compounds unambiguously. For instance, the difference between 'vanadium(IV) oxide' and 'vanadium(V) oxide' signals different chemical properties and structures due to the distinct charges on the vanadium ion, which then lead to different formulas: VO2 for vanadium(IV) oxide and V2O5 for vanadium(V) oxide.

Balancing ionic charges can be likened to solving a puzzle where the pieces must fit together perfectly to complete the picture. Just as puzzle pieces have unique shapes that must be matched, ions have specific charges that must be balanced to form a stable compound. The concept was exemplified in our exercise where the formula for vanadium(V) oxide was determined to be V2O5. This is because each vanadium ion carries a 5+ charge and each oxygen ion carries a 2- charge. To balance the charges, two vanadium ions (a total of 10+ charge) combine with five oxide ions (a total of 10- charge), resulting in a neutral compound.

Mastering the art of balancing charges is essential for students as it lays the groundwork for writing correct formulas and understanding the stoichiometry of chemical reactions. The step-by-step solutions offer a clear pathway to interpret and balance the charges for students, thus enhancing their learning experience and ensuring they can apply this knowledge effectively.