Write formulas for the ionic compounds formed from (a) sodium and oxide ions; (b) potassium and sulfate ions; (c) silver and fluonide ions; (d) zinc and nitrate ions; (e) aluminum and sulfide ions.

Understanding how to write chemical formulas for ionic compounds is essential in mastering chemistry. An ionic compound is composed of a cation, which is a positively charged ion, and an anion, which is a negatively charged ion. These ions bond together to form a neutral compound.

In writing the formula of an ionic compound, the goal is to combine the ions in proportions such that the positive and negative charges balance out. The sum of the charges must equal zero. When you look at the provided exercise, you can see that this balance is achieved by adjusting the ratio of cations to anions. For example, to balance the charges for sodium (Na+) and oxide (O^2-), we need two sodium ions for every oxide ion, resulting in the formula Na2O.

Identifying Ionic Charges

Each ion has a characteristic charge based on its position in the periodic table. In our exercise, sodium (Na) loses one electron to form a +1 cation, while oxide (O) gains two electrons to form a -2 anion.

Finding the Correct Ratios

To determine the ratio of ions, compare their charges. The number of ions needed from either side will depend on the necessity to balance the overall charge. In the exercise with zinc (Zn^2+) and nitrate (NO3-), one zinc cation, which has a +2 charge, balances with two nitrate anions each with a -1 charge, leading to the formula Zn(NO3)2.

Pairing cations and anions to form ionic compounds can be visualized like solving a puzzle; each piece must fit together perfectly. The cation, a 'puzzle piece' with one or more positive charges, must be matched with an anion 'piece' carrying negative charges. Their charges must cancel each other out for the compound to be stable. In our exercise, aluminum (Al^3+) requires three positive charges to be neutralized, which are balanced by two sulfide anions (S^2-), hence the resulting chemical formula is Al2S3. This pairing indicates that two aluminum ions will pair with three sulfide ions to form a stable ionic compound.

The naming of chemical compounds, known as chemical nomenclature, adheres to a set of rules and conventions to ensure clear and concise communication. Ionic compounds are typically named by stating the cation first, followed by the anion. For monatomic anions, the ending '-ide' is added to the root of the element's name. The exercise includes potassium (K+) and sulfate (SO4^2-), where potassium is the cation and sulfate is the polyatomic anion. Following the rules, the name of the compound is 'potassium sulfate,' and the formula, as determined by the ion charges and ratios, is K2SO4.