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Download Activity 151-4 Nomenclature for Chemical Compounds
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Activity 151-4 Nomenclature for Chemical Compounds Directions: This Guided Learning Activity (GLA) focuses on naming chemical compounds. Part A discusses the rules for naming ions, Part B introduces naming ionic and molecular compounds, and Part C discusses rules for naming acids. The worksheet is accompanied by instructional videos. See http://www.canyons.edu/Departments/CHEM/GLA/ for additional materials. Part A – Naming Ions To correctly name chemical compounds, first one must be familiar with the names of common ions. Recall that many ions that form are simply elemental atoms that have gained or lost an electron. In general, when a metal atom loses one or more electrons to form an ion, the name of the metal is retained and the word ‘ion’ is added. For example, Calcium (Ca) becomes Calcium ion (Ca2+). When metal has more than one common charge, the state is given as a Roman numeral in the name. Copper (Cu), for example has two common oxidation states, copper (I) ion (Cu+) and copper (II) ion (Cu2+). To name a nonmetal ion, the ending for the elemental name is dropped, and ‘ide’ is added in its place. For example, fluorine (F) becomes fluoride (F-) when it gains an extra electron. Example #1. Name these ions. Mg2+ N3- As2+ S2- P3- _______ _______ _______ _______ ______ Many compounds form from polyatomic ions, and it’s important to be able to name these ions, and know their formulas and charges. The following are a short list of commonly occurring ions that you should know for Chemistry 151. The complete list of ions that Chemistry 151 students are expected know is provided at the end of this GLA. Common Polyatomic Ions NO3 - CO32ClO3 - nitrate NH4+ carbonate OH- chlorate SO42- sulfate PO43- phosphate Chemistry Guided Learning Activities Activity 151 – 4 C2H3O2 ammonium hydroxide - acetate College of the Canyons Page 1 of 6 Pneumonic devices can be useful in memorizing polyatomic ions. For example, to recall some of the most common polyatomic ions, use the following pneumonic, where the number of consonants in each word represents the number of oxygen atoms present and the number of vowels represents the charge: Nick the Camel ate a Clam Supper in Pheonix. NO3- CO32- ClO3- SO42- PO43- The accompanying video will give some more tips to help memorize polyatomic ions. Example #2. Name these ions. NO2- ClO4- _______ _______ NH4+ HCO3- BrO3- _______ _______ ______ Part B – Classifying Compounds for Nomenclature Chemicals are named differently based on their classification. This GLA discusses how to name three classes of compounds: ionic compounds, covalent compounds and acids. It is important to recognize the class of compound before applying the naming rules that will be discussed in Parts C and D. To classify each type of compound look for the following characteristics: Ionic Compounds – contains metal and nonmetal elements, or polyatomic ions are present Covalent Compounds – only nonmetals are present in compound Acids – chemical formula begins with an ‘H’. Example #3. Classify each of the compounds as an ionic compound, a covalent compound or an acid. a. BaCl2 ______________________ d. CH4 ______________________ b. MnO2 ______________________ e. H2S* ______________________ c. H3AsO4 ______________________ f. CH3OH ______________________ *H2S can be named as either a molecular compound or an acid, depending on its phase. Chemistry Guided Learning Activities Activity 151 – 4 College of the Canyons Page 2 of 6 Part C – Naming Ionic and Molecular Compounds For ionic compounds, the names of the ions are simply combined to yield the name of the compound. Recall that when multiple charges are present, the charge of an ion is given as a Roman numeral in the name. (e.g. Fe3+ is iron (III) ion.) The diagram above summarizes these rules. Example #4. Name these compounds: Na2CO3 CaSO4 NH4OH SrCl2 Cu2O _______ _______ _______ _______ ______ To name molecular compounds, the name of the first element listed in the formula is given, followed by the name for the second element. The ending for the second element is changed to ‘ide’. For molecular compounds, compounds can form with different ratios of the elements involved (e.g. CO and CO2 both form). To clarify the number of each atom present, the following prefixes are used: Prefixes for Covalent Compounds 1 mono- 5 penta- 8 octa- 2 di- 6 hexa- 9 nona- 3 tri- 7 hepta- 10 deca- 4 tetra- Using these prefixes, CO would be named ‘monocarbon monoxide,’ yet you probably know this compound as carbon monoxide. In general, the prefix ‘mono’ is dropped and is only used in cases where extra clarification may be necessary. In this case, we retain ‘monoxide’ to distinguish the compound from another common compound, carbon dioxide. Chemistry Guided Learning Activities Activity 151 – 4 College of the Canyons Page 3 of 6 Example #5. Name these compounds: CCl4 P2O5 SO3 SiC NCl3 _______ _______ _______ _______ ______ Finally, there are two compounds for which the common name is used almost universally. These are: H2O called __________________, and NH3 called ____________________. Part D – Naming Acids Acids are compounds that increase the concentration of H3O+ ions in solution. They are recognizable as acids because the hydrogen (H) that dissociates is written at the beginning of the chemical formula. In this class two types of acids are discussed: binary acids that consist of only two elements (H + another nonmetal), and oxyacids (H + a polyatomic ion that contains oxygen). To name binary acids, the root of the nonmetal name is modified by adding the prefix ‘hydro’ and the ending ‘-ic acid’. Oxyacids are modified by dropping the ‘-ate’ or ‘-ite’ ending and adding ‘-ic acid’ or ‘-ous acid’, respectively. Example #6. Name these acids: HNO3 _______ HCl _______ Chemistry Guided Learning Activities Activity 151 – 4 H2SO3 H2CO3 H3As _______ _______ ______ College of the Canyons Page 4 of 6 Part D – Extra Practice Write the name for each of these compounds. MgCO3 Fe2(CO3)3 PF5 SO3 Al(OH)3 (NH4)3PO4 PbBr2 PbBr4 P4O10 HClO2 Fe(OH)3 NaC2H3O2 Na2SO4 NaHSO4 HBr NO2 NaHCO3 Fe(ClO2)2 HC2H3O2 CuSO4 Give the chemical formula for each of these compounds. lithium oxide zinc cyanide tin (II) sulfide tin (IV) sulfide beryllium chloride calcium oxide hydroiodic acid zinc nitride mercury (I) chloride magnesium hydroxide ammonium bicarbonate sodium hydrogen phosphate vanadium (V) oxide ammonia copper (II) phosphite xenon tetrabromide aluminum sulfide gold (III) nitrate phosphoric acid barium nitrate potassium carbonate manganese (II) acetate magnesium hydrogen sulfite silver fluoride Chemistry Guided Learning Activities Activity 151 – 4 College of the Canyons Page 5 of 6 Chemistry Guided Learning Activities Activity 151 – 4 College of the Canyons Page 6 of 6
