The following acids are also used in chemical laboratorics, although they are less common than those in the preceding exercise. Write the formulas of (a) perchloric acid; (b) hypochlorous acid; (c) hypoiodous acid; (d) hydrofluoric acid; (c) phosphorous acid; (f) periodic acid.

Understanding chemical nomenclature, which is essentially the naming system of compounds, is crucial for students to write chemical formulas accurately. The names of acids often give clues about their composition and structure. For instance, the prefix ‘hydro-’ in hydrofluoric acid tells us that the compound is an acid that consists of hydrogen and a non-metal. Similarly, the prefix ‘per-’ as in perchloric acid indicates a higher oxygen content than in chloric acid.

Using the example of perchloric acid, the root ‘chlor’ refers to the element chlorine, and the suffix ‘-ic’ suggests that it is in the form of its highest common oxidation state, in this case, perchlorate \textbf{(ClO4\(^-\))}. Learning to recognize these prefixes, roots, and suffixes can simplify the process of writing chemical formulas. The key is to match the names of acids with the appropriate anion and combine with hydrogen ions to balance the charge.

When it comes to determining the formula of acids, there's a systematic method students can follow. Firstly, identify the central element and the associated oxyanion if it's an oxyacid. For example, in hypochlorous acid, ‘hypo-’ indicates fewer oxygen atoms than the common oxyacid of chlorine, which is chlorous acid. The oxyanion for hypochlorous acid is thus hypochlorite \textbf{(ClO\(^-\))}.

Once the oxyanion is established, the formula can be determined by adding enough hydrogen ions (\textbf{H\(^+\)}) to neutralize the negative charge of the anion, resulting in a neutral compound. Keep in mind that some acids, like phosphorous acid, have a more complex polyatomic anion, such as phosphite \textbf{(HPO3\(^{2-}\))}, which requires three hydrogen ions for charge balance, forming \textbf{H3PO3}. Recognizing these details is an essential step before you can successfully write the correct formula for an acid.

Having knowledge of the periodic table charges is indispensable for writing chemical formulas. Elements in the periodic table are organized in a way that allows us to infer their common ion charges based on their group (column). For instance, halogens like chlorine typically form anions with a charge of \(^-1\), as in the case of hypochlorous acid (\textbf{ClO\(^-\)}).

Transition metals can have multiple possible charges, which is often indicated in the compound’s name using Roman numerals. Nonmetals found on the right side of the periodic table usually form anions with negative charges. Understanding these patterns provides a foundation for predicting the charge balance required in chemical compounds. The concept of electronegativity is also important, as it influences how atoms will gain or lose electrons to form ions, which is the basis of writing formulas for acids and other compounds.