Write formulas for (a) aluminum phosphate; (b) barium nitrate dihydrate; (c) silicon disulfide; (d) sodium phosphide; (e) perchloric acid; (f) copper(II) oxide; (g) hydroiodic acid; (h) silver(l) sulfate.

Understanding the names of chemical substances and how to write them accurately is crucial in chemistry. This is known as chemical nomenclature. Chemical nomenclature encompasses rules and conventions for naming compounds so that scientists can communicate with clarity and precision.

For ionic compounds, like aluminum phosphate or sodium phosphide, nomenclature involves the combination of the cation (positive ion) and anion (negative ion) names. In the case of molecules with transition metals, such as copper(II) oxide, the Roman numeral indicates the oxidation state of the metal.

For acids, like perchloric acid or hydroiodic acid, the name usually reflects the anion they form when dissolved in water. The prefix 'hydro-' is used when the acid is formed from just hydrogen and one other element, and a root based on the anion's name with a suffix like '-ic' commonly follows.

When composing ionic compound formulas, it is important to correctly ascertain the ratio of cations to anions so that the overall electrical charge of the compound is neutral. The subscript numbers in the formula reflect this ratio and are determined by balancing the total positive and negative charges.

Take barium nitrate dihydrate (Ba(NO3)2.2H2O) as an example. Barium contributes a +2 charge and each nitrate anion carries a -1 charge, hence, two nitrate ions are needed to balance the charge from one barium ion. The 'dihydrate' signifies the presence of two water molecules associated with each formula unit of the salt. The correct formula depicts that stoichiometric relationship.

Balancing chemical charges is a fundamental aspect of writing chemical formulas. This process involves ensuring that the total positive charge balances the total negative charge in the compound, resulting in an electrically neutral molecule.

Let's take the case of sodium phosphide (Na3P) as an illustration. Sodium ions have a +1 charge, and the phosphide ion has a -3 charge. In order to achieve a net charge of zero, three sodium ions are needed for every one phosphide ion. The subscript numbers in the chemical formula, therefore, reflect the necessary quantities of each ion to balance the charges.