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Chemistry 20

Chemistry 20 · Worksheets

Names and formulas

Ten questions of mixed difficulty, covering Names and formulas. Print it, or work through it on screen — the answer key starts on its own page.

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Names and formulas

Chemistry 20 · maddyhelps.com

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Circle the best answer for each question. Show your work in the space provided.

  1. The IUPAC name of CH₃CH₂CH₂CH₃ is

    1. a) butene
    2. b) butane
    3. c) methane
    4. d) propane

  2. The formula for sodium chloride is

    1. a) NaCl₂
    2. b) Na₂Cl
    3. c) NaCl
    4. d) Na₂Cl₂

  3. The formula for ammonium sulfate is

    1. a) N₂H₈SO₄
    2. b) (NH₄)₂(SO₄)₂
    3. c) NH₄SO₄
    4. d) (NH₄)₂SO₄

  4. The formula for iron(II) phosphate is

    1. a) Fe₃(PO₄)₂
    2. b) Fe₂PO₄
    3. c) FePO₄
    4. d) Fe₂(PO₄)₃

  5. The formula for aluminum oxide is

    1. a) AlO₃
    2. b) AlO
    3. c) Al₂O₃
    4. d) Al₃O₂

  6. The formula for calcium chloride is

    1. a) CaCl₂
    2. b) CaCl
    3. c) Ca₂Cl₃
    4. d) Ca₂Cl

  7. The name of N₂O₄ is

    1. a) dinitrogen tetroxide
    2. b) nitrogen tetroxide
    3. c) nitrogen(IV) oxide
    4. d) dinitrogen tetraoxide

  8. Of these, the molecular compound is

    1. a) MgBr₂
    2. b) K₂O
    3. c) CO
    4. d) NaCl

  9. The name of FeCl₃ is

    1. a) iron chloride
    2. b) iron(III) chloride
    3. c) iron(II) chloride
    4. d) triiron chloride

  10. The name of CO₂ is

    1. a) monocarbon dioxide
    2. b) carbon oxide
    3. c) carbon(IV) oxide
    4. d) carbon dioxide

Answer key · Names and formulas

Chemistry 20 · maddyhelps.com

  1. b) butane — Count the carbons: four, which is the prefix but-. Every bond between carbons is single, so the ending is -ane. An -ene ending would mean a double bond somewhere in the chain.
  2. c) NaCl — Sodium forms Na⁺ and chlorine forms Cl⁻. One of each balances the charge, so the formula unit is NaCl. Ionic formulas are always the simplest whole-number ratio.
  3. d) (NH₄)₂SO₄ — Ammonium is NH₄⁺ and sulfate is SO₄²⁻, so two ammoniums balance one sulfate. A polyatomic ion that is needed more than once goes in brackets, so the subscript applies to the whole group.
  4. a) Fe₃(PO₄)₂ — The numeral says Fe²⁺, and phosphate is PO₄³⁻. Balancing to six units of charge needs three irons and two phosphates. Fe₂(PO₄)₃ would be iron(III) phosphate.
  5. c) Al₂O₃ — Al³⁺ and O²⁻ need a lowest common multiple of six units of charge: two aluminums and three oxygens. Crossing the charges over gives the subscripts directly.
  6. a) CaCl₂ — Calcium is Ca²⁺ and chloride is Cl⁻, so two chlorides are needed to balance one calcium. The subscript comes from balancing charge, not from the name.
  7. a) dinitrogen tetroxide — Both elements take prefixes in a molecular compound: di- for two nitrogens and tetr- for four oxygens. The a is dropped before the vowel, giving tetroxide rather than tetraoxide.
  8. c) CO — Carbon and oxygen are both non-metals, so CO is molecular. The other three each pair a metal with a non-metal, which makes them ionic.
  9. b) iron(III) chloride — Iron is multivalent, so the Roman numeral is required and states the charge on the metal. Three Cl⁻ means the iron must be Fe³⁺. The numeral gives the charge, not the number of chlorines.
  10. d) carbon dioxide — Molecular compounds use prefixes because the same two elements can combine in several ratios — CO and CO₂ are different substances. The prefix mono- is dropped on the first element.