Question

Which of the following names are incorrect? Write the correct name if possible; if there are several possibilities, write them all. If the name is correct, write the formula. (a) sulfate of barium (b) potassium bromide (c) iron(III) carbonate (d) aluminum(III) phosphate (e) calcium selenide (f) trimagnesium diphosphate (g) dilithium difluoride

Short answer

(a) 'barium sulfate' (BaSO4), (b) Correct (KBr), (c) Correct (Fe2(CO3)3), (d) Correct (AlPO4), (e) Correct (CaSe), (f) 'magnesium phosphate' (Mg3(PO4)2) or 'magnesium hydrogen phosphate' (MgHPO4), (g) 'lithium fluoride' (LiF)

Step-by-step solution

Check each compound name

Analyze each given compound name to determine if it is correctly named according to the IUPAC nomenclature of inorganic chemistry. Correct names should reflect the charges of the ions involved and use the right prefixes for molecular compounds.

Correct Incorrect Names

For each incorrect compound name, provide the correct name based on the standard nomenclature rules. If the correct name corresponds to more than one possible formula, write down all possibilities.

Provide Formulas for Correct Names

When a name is correct, write down the corresponding chemical formula by combining the correct ions with their appropriate subscripts to balance the charges.

Analyze each given name individually

(a) 'sulfate of barium' is not using modern IUPAC nomenclature. The correct name is 'barium sulfate' and the formula is BaSO4. (b) 'potassium bromide' is correct, and the formula is KBr. (c) 'iron(III) carbonate' is correct, and the formula is Fe2(CO3)3. (d) 'aluminum(III) phosphate' is correct, and the formula is AlPO4 (since the Roman numeral III indicates the valency of aluminum, which balances with the single negative charge of the phosphate ion). (e) 'calcium selenide' is correct, and the formula is CaSe. (f) 'trimagnesium diphosphate' is incorrect because the name suggests a 3:2 magnesium to phosphate ratio, which doesn't reflect the common ratios for phosphate salts. The correct names could be 'magnesium phosphate' with the formula Mg3(PO4)2 or 'magnesium hydrogen phosphate' with the formula MgHPO4. (g) 'dilithium difluoride' is incorrect because the prefix 'di-' suggests two lithium atoms, which would result in an incorrect charge balance. The correct name is simply 'lithium fluoride', and the formula is LiF.

Key concepts

IUPAC Nomenclature

Understanding the International Union of Pure and Applied Chemistry (IUPAC) nomenclature is key to naming chemical compounds correctly. IUPAC provides a systematic way to name chemical substances, both organic and inorganic. At its core, the nomenclature involves identifying the chemical elements present and the compound's structure or composition.

For instance, when we look at sulfate of barium, using IUPAC naming conventions, we identify the cation (barium, Ba²⁺) and the anion (sulfate, SO₄²⁻) and combine them correctly to form the name 'barium sulfate'. Similarly, for a compound like iron(III) carbonate, we indicate the oxidation state of iron (III, representing a 3+ charge) and the carbonate anion (CO₃²⁻) to properly name and formulate it as Fe₂(CO₃)₃.

Rules such as using Roman numerals for oxidation states and proper ionic subscripts are fundamental to IUPAC naming. By following such guidelines, we achieve a universal understanding and naming methodology that avoids ambiguity in the chemical world.

Chemical Formula Writing

Writing chemical formulas is an essential skill in chemistry that requires a clear understanding of the elements involved and their respective charges. A correct formula reflects the perfect balance between positive and negative charges, leading to a neutral compound.

For example, in the case of potassium bromide, the correct chemical formula is KBr because potassium is a monovalent cation (K⁺) and bromide is a monovalent anion (Br⁻); they combine in a 1:1 ratio to balance the charges. For a compound like trimagnesium diphosphate, the name implies a ratio of magnesium to phosphate that doesn't exist in common phosphate salts, leading us to correct it to either 'magnesium phosphate' (Mg₃(PO₄)₂) or 'magnesium hydrogen phosphate' (MgHPO₄).

It's essential to memorize the common charges of cations and anions to properly write formulas. Additionally, familiarity with polyatomic ions, like sulfate or phosphate, is necessary because they occur frequently in inorganic compounds.

Inorganic Chemistry

Inorganic chemistry is the branch of chemistry dealing with compounds that do not primarily consist of hydrocarbons, focused on the behavior and synthesis of inorganic and organometallic compounds.

Understanding inorganic nomenclature and formula writing, as in the case of dilithium difluoride, which should be correctly named 'lithium fluoride' (LiF), is a fundamental aspect of inorganic chemistry. Here, 'di-' in the original name incorrectly implies two atoms of lithium, but the correct ratio for charge balance is 1:1. This study area includes knowledge of elements, their properties, how they react with each other, and the structures they form.

Inorganic compounds, such as aluminum(III) phosphate (AlPO₄), often have specific naming rules that stem from their ionic nature, coordination compounds, crystal field theory, and other overarching principles in this field of chemistry. The ability to name these compounds correctly and write their formulas accurately is a practical application of inorganic chemistry principles.