Y1 · X · #12Nomenclature

Nomenclature – binary compounds – cations with variable charge (II)

Nomenclature – Binary Compounds: Cations with Variable Charge (Part II)

Last lesson you met the idea that some metals — mostly transition metals — don't have a fixed charge on their cation, so we need a Roman numeral to say exactly which ion is present (Talbot, p.130). Today we go a step further: working out the charge yourself from the formula, and meeting a few "extra" metals outside the transition block that also need Roman numerals.

Quick recap

Fixed-charge metals (group 1, group 2, Al³⁺, Zn²⁺, Ag⁺) never need a Roman numeral.
Variable-charge metals (many transition metals, plus a few p-block metals like Pb and Sn) need a Roman numeral showing their oxidation state in that particular compound.
The Roman numeral goes straight after the metal's name, in brackets, with no space before the b

Ask ChemBuddy about this →

Source excerpts

From Chemistry for the IB Diploma 3e · Talbot

p.130relevance 18.2

S2: Models of bonding and structure 118 Examples of compounds containing these ions are potassium oxide, K2O [2K+ O2−]; potassium nitride, K3N [3K+ N3−]; potassium cyanide, KCN [K+ CN−]; and potassium hydroxide, KOH [K+ OH−]. Ammonium chloride has the formula NH4Cl [NH4 + Cl−]. What are the names of the compounds with the formulas CoCl 2 and BaCl2? Answer Cobalt is a transition…

p.172relevance 16.5

S2: Models of bonding and structure 160 TOK What is the role of nomenclature and terminology in the chemical community? The role of IUPAC (International Union of Pure and Applied Chemistry) is interesting to consider in relation to theory of knowledge. One of the primary roles of IUPAC is to recommend: unambiguous, uniform, and consistent nomenclature and terminology for specif…

p.126relevance 16.1

S2: Models of bonding and structure 114 S 2 .1 The ionic model Structure 2 Models of bonding an d structure • What determines the ionic nature and properties of a compound? Guiding question SYLLABUS CONTENT By the end of this chapter, you should understand that:  when metal atoms lose electrons, they form positive ions called cations  when non-metal atoms gain electrons, they…

p.289relevance 15.7

S3.2 Functional groups: classification of compounds 277 Nomenclature of organic compounds To clearly identify organic molecules, a systematic method of naming has been developed by IUPAC (the International Union of Pure and Applied Chemistry). In the IUPAC system of nomenclature, the names of organic molecules correlate with their structures and have three parts determined as s…