Exam logistics

• Exam timing and logistics
  • Exam is next Thursday; it starts at the beginning of class and runs for 50 minutes.
  • A practice test is available on iCollege, under a section named something like "Old Pitts" and/or related to naming compounds.
  • If you can’t see the practice test, check that the module for naming compounds was clicked or opened.

Big idea: Nomenclature with metals that have multiple charges

• Key goal of today’s content
  • Nomenclature where the metal can have multiple oxidation states (charges).
  • Distinguish ionic vs covalent naming conventions.
  • You either get the formula or you get the name and you have to provide the opposite (name -> formula or formula -> name).
• Core focus areas introduced
  • A lot of examples involve oxides and related compounds (e.g., oxide, lithium phosphide).
  • Some examples include formations like CaO or Li2S (as implied by discussion of where these go on a chart or in a naming exercise).
  • Review material is accessible in the course system (iCollege) under the appropriate module.

How to distinguish different cases in naming

• General approach
  • For compounds that involve a metal and a nonmetal, naming typically starts with the metal (and, for metals with multiple oxidation states, includes a roman numeral to indicate the oxidation state).
  • For covalent (two nonmetals) compounds, you name both elements (with prefixes to indicate the number of atoms), and you may sometimes omit the prefix “mono-” for the first element.
• The counting logic for oxidation states (how many charges the metal has)
  • You balance charges to determine the metal’s oxidation state.
  • Typical oxidation state options range around 1, 2, 3, 4, etc. If you have multiple possible states, use the charge balance with the nonmetal or polyatomic ion to determine the correct state.
  • Example reasoning framework mentioned in class:
  • If you have a metal M and a nonmetal X with a certain charge, solve for the metal’s oxidation state x from the equation:
    x + n imes ( ext{charge of X}) = 0
  • Then assign the name as M(oxidation state)X, e.g., iron(III) bromide for FeBr3 where Br is -1 and Fe must be +3.

Specific examples discussed in class

• Iron(III) bromide
  • Formula: ext{FeBr}_3
  • Reason: bromide ion has charge -1; with three bromides, total anion charge is -3; the iron must be +3 to balance.
  • Named as: iron(III) bromide.
• Uranium(IV) oxide
  • Oxidation state reasoning:
  • Oxygen is -2 per atom. To balance two oxygens: 2 imes (-2) = -4.
  • Therefore the uranium must be +4 to balance to zero total charge.
  • Formula: ext{UO}_2
  • Named as: uranium(IV) oxide.
  • Concept reinforced: the oxidation state of the metal is determined by the known charges of the anion(s).
• Mono- prefixes and traditional naming conventions
  • In many traditional ionic names, the prefix “mono-” is omitted (e.g., not saying “monoxide” for a single oxide).
  • In covalent (molecular) naming, prefixes indicate the number of atoms; however, many instructors or regions also omit the prefix for the first element (e.g., NO vs NO2 naming rules vary by practice).
• Examples of common diatomic/polyatomic oxides
  • NO2 is nitrogen dioxide.
  • N2O4 is dinitrogen tetroxide.
  • N2O5 is dinitrogen pentoxide.
• Important reminder about formula vs name ambiguity
  • Ions vs neutral molecules can share the same formula notation in some cases; careful attention to context (ionic compound vs molecular species) is essential to avoid misnaming (e.g., nitride as an ion vs nitrogen-containing molecule).
  • Nitride vs nitrogen dioxide example from class:
  • Nitride (N^{3-}) is an ion in ionic compounds with metal cations.
  • NO2 is a neutral covalent molecule (a gas) with different properties from nitride salts.
• Nitride vs nitride ion properties (conceptual gist from lecture)
  • The nitride ion forms salts that are ionic in nature (and can be soluble/part of ionic substances).
  • NO2, by contrast, is a covalent molecule (a gas) with very different properties.
  • This contrast highlights how charge, bonding, and phase determine properties and naming conventions.
• Noting formatting conventions in naming
  • In the notebook or on iCollege, there was emphasis on no spaces in certain representations, and on how to format parentheses when writing formulas (habits shown during the discussion of FeBr3 and related compounds).

Nitrogen-containing species and careful naming tips

• Distinguish nitrogen oxides by formula and context
  • NO_2 = nitrogen dioxide (a gaseous covalent molecule).
  • N2O4 = dinitrogen tetroxide (a covalent molecule, often in equilibrium with NO2 in air).
  • N2O5 = dinitrogen pentoxide (a covalent molecule).
• Common source of confusion: ions vs neutral species with similar formulas
  • Be mindful that the same string of symbols can refer to different species depending on charges and context (e.g., nitride ion vs nitrite/nitrate species).
• Conceptual takeaway
  • The presence or absence of charge changes the chemical family (ionic vs covalent) and the naming conventions dramatically, even when the underlying elemental composition seems similar.

Acids: three kinds and their naming conventions

• Three kinds of acids discussed 1) Binary (hydro- acids)
  • General rule: acids formed from hydrogen and a nonmetal where the anion ends in -ide (e.g., Cl-, Br-, I-).
  • Names use the hydro- prefix and end in -ic acid (e.g., hydrochloric acid, hydrobromic acid, hydroiodic acid).
  • Examples mentioned: HCl (hydrochloric acid), HBr (hydrobromic acid), HI (hydroiodic acid).
  • Formula examples to relate: ext{HCl}, ext{HBr}, ext{HI}.
    2) Oxyacids (oxacids) with oxyanions like nitrate, nitrite, chlorate, etc.
  • Examples discussed: HNO2 (nitrous acid) and HNO3 (nitric acid).
  • Also mentioned: HIO3 (iodic acid) as another oxyacid example.
  • Naming approach: based on the anion name; -ate suffix becomes -ic acid, -ite suffix becomes -ous acid (e.g., NO3− → nitric acid; NO2− → nitrous acid).
  • Related examples to keep in mind:
    • ext{HNO}_3
      ightarrow ext{nitric acid} (from nitrate, NO3−)
    • ext{HNO}_2
      ightarrow ext{nitrous acid} (from nitrite, NO2−)
    • ext{HIO}_3
      ightarrow ext{iodic acid} (from iodate, IO3−)
      3) Organic acids
  • Mentioned as a category we don’t cover deeply in this course because organic chemistry is not the focus of this class; the lab may touch on basics.
• Key linguistic notes from the lecture
  • The term "hydro" comes from hydrogen and is used for binary acids, not because the acid necessarily involves water.
  • The suffixes in oxyacids depend on the oxidation state of the central element as reflected in the corresponding anion name (ate → -ic, ite → -ous).
• Quick mapping examples (for self-check)
  • ext{HCl}
    ightarrow ext{hydrochloric acid}
  • ext{HBr}
    ightarrow ext{hydrobromic acid}
  • ext{HI}
    ightarrow ext{hydroiodic acid}
  • ext{HNO}_3
    ightarrow ext{nitric acid}
  • ext{HNO}_2
    ightarrow ext{nitrous acid}
  • ext{HIO}_3
    ightarrow ext{iodic acid}
• Final note on acid naming in labs
  • In practice, acid naming helps predict chemical behavior in aqueous solution and is essential for lab protocol discussions and safety data interpretation.

Practical tips and takeaways for exams

• Know how to determine oxidation states from formulae when metal cations have multiple possible charges (use charge balance with anions).
• Remember the common examples and their formulas, e.g.:
  • ext{FeBr}_3 (iron(III) bromide),
  • ext{UO}_2 (uranium(IV) oxide),
  • ext{NO}2, ext{N}2 ext{O}4, ext{N}2 ext{O}_5 (nitrogen oxides) for practice in distinguishing ionic vs covalent contexts.
• Practice both directions: given a name, write the formula; given a formula, write the name (with oxidation state in parentheses for transition/metals with multiple possible charges).
• Remember the general acid naming rules and the special “hydro-” convention for binary acids vs oxyacids naming with -ic/-ous suffixes.
• Use the balancing approach with simple charge-balance equations to deduce oxidation states, especially when you see oxides, sulfides, or halides.
• Distinguish nitride (N^{3-}, ionic) from nitrogen oxides like NO2 (covalent gas) to avoid misnaming and misapplying properties.
• The mono- prefix discussion is about conventions; in ionic names, mono- is typically omitted; in covalent prefixes, mono- is sometimes omitted for the first element but used for certain second elements depending on the instructor.
• Real-world relevance
  • These naming rules underpin chemistry lab work, material science (oxidation state analysis), and environmental chemistry where nitrogen oxides and oxides of metals are common.
• Ethical/practical considerations
  • Accurate naming is essential for safety data, chemical inventory, and lab reporting; misnaming can lead to misinterpretation of chemical behavior and hazards.

Quick practice prompts (to apply today)

• Name the following compounds and/or give their formulas:
  • ext{FeBr}3 → name: ___
  • ext{UO}2 → name: ___
  • NO2, N2O4, N2O_5 → provide common names
  • ext{HNO}3 → name: ___
  • ext{HNO}2 → name: ___
  • ext{HIO}3 → name: ___
• Ionic vs covalent distinction: provide one example of each with formulas and why the naming differs.
• Explain why uranium in ext{UO}_2} is considered +4 and how the oxidation state was determined.
• For binary acids, convert the following to acid names: HCl, HBr, HI.
• For oxyacids, convert the following to acid names and identify the parent anion: HNO3, HNO2, HIO3.