Naming and Writing Formulas for More Complex Compounds Section 4.2 Group: 6 Period: 4 November 19,2009

Background and Introduction Nomenclature can be defined as the terminology of chemical compounds. It represents the basic "language of chemistry”. Nomenclature is a concept in Chemistry that uses a wide set of rules to help guide us in naming compounds, and constructing formulas. We learn to memorize polyatomic ions and their Ion to learn how to conduct much more complex formulas, and also to help us determine how to name our compounds.

Polyatomic Ions Polyatomic ions are charged energies composed of several atoms bound together. Polyatomic ions have special names that must be memorized in order to name the compounds containing them. There are polyatomic anions that contain an atom of a given element and different numbers of oxygen atoms, which are called oxyanions. Most common polyatomic anions occur in "families". All members of the family share the same central element and the same charge. There are three common types of variations within the family: Different members of the family can have numbers of oxygens. Each member of the family can combine with hydrogen ions to partially neutralize their negative charge.

Question # 1: Polyatomic Ions What are oxyanions? And give 2 examples.

Naming Compounds with Polyatomic Ions & Naming Binary Molecular Compounds Common Naming Practices: To name the compounds containing polyatomic ions : Learn to recognize the polyatomic ion in the compounds. Learn the composition and charge of each of the polyatomic ion. Learn that when a metal is present, that forms more than one cation, a Roman numeral is used to specify the cation charge. . For example, the compound FeSO4 is called iron (II) sulfate, because it contains Fe2+ ( to balance the 2- charge on SO42-). Note that to determine the charge on the iron cation, you must know that sulfate has a 2- charge. Naming Binary Molecular Compounds: Molecular compounds are formed from the covalent bonding between non-metallic elements. The nomenclature for these compounds is described in the following set of rules: The more positive atom is written first (the atom which is the furthest to the left and to the bottom of the periodic table) . The more negative second atom has an "-ide" ending. Each prefix indicates the number of each atom present in the compound. Then when you see the formula NH4C2H3O2, you should immediately recognize its two “parts”: NH4\C2H3O2. The correct name is ammonium acetate. Common Naming Practices : modify stem name with: meaning examples -ate a common form, containing oxygen chlorate, ClO3- nitrate, NO3- sulfate, SO42- -ite one less oxygen than -ate form chlorite, ClO2- sulfite, SO32- nitrite, NO2- per-, -ate same charge, but contains one more oxygen than -ate form perchlorate, ClO4- perbromate, BrO4- hypo-, -ite same charge, but contains one less oxygen than the -ite form hypochlorite, ClO- hypobromite, BrO- Naming Binary Molecular Compounds: Number of Atoms Prefix 1 mono 6 hexa 2 di 7 hepta 3 tri 8 octa 4 tetra 9 nona 5 penta 10 deca Examples: CO2 = carbon dioxide P4S10 = tetraphosphorus decasulfide

Question # 2:Naming Compounds with Polyatomic Ions & Naming Binary Molecular Compounds 2. When more than one polyatomic ion appears in a chemical formula, what are used to enclose the ion and what is written after the ion is enclosed?

Naming Acids Substances that are, when dissolved in water produce H+ ions are called acids. An acid can be viewed as a molecule with one or more H+ ions attached to an anion. Acids were first recognized by the sour taste of their solutions. Rules for Naming Acids 1. If the anion does not contain oxygen, the acid is named with the prefix hydro- and the suffix- ic attached to the root name for the element. For example, when gaseous HCI, HCN, AND H2S are dissolved in water, they form the following acids: Acid Anion Name HCI CI- hydrochloric acid HCN CN- hydrocyanic acid H2S S2- hydro sulfuric acid The application of rule 2 can be seen in the names of the acids of the oxyanion of chlorine, as shown below. 2.When the anion contains oxygen, the acid name is formed from the root name of the central element of the anion or the anion name, with a suffix of –ic or ous. When the anion name ends in – ate, the suffix – ic is used. For example, Acid Anion Name H2SO4 SO42- (sulfate) sulfuric acid H3PO4 PO43- (phosphate) phosphoric acid HC2H3O2 C2H3O2-(acetate) acetic acid Acid Anion Name HCIO4 percholorate perchloric acid HCIO3 chlorate chloric acid HCIO2 chlorite chlorous acid HCIO hypochlorite hypochlorous acid 3. When the anion name ends in –ite, the suffix-ous is used in the acid name. For example, Acid Anion Name H2SO3 SO32- (sulfite) sulfurous acid HNO2 NO2- (nitrite) nitrous acid

Question # 3: Naming Acids 3. An acid is a substance that produces hydrogen ions (H+) in solution; a proton donor. When an anion contains oxygen, the acid name is formed from the root of what and with what suffixes or suffix?

Naming Acids With and Without Oxygen Names of Some Oxygen-Containing Acids Names of Acids That Do Not Contain Oxygen Acid Name HF Hydrofluoric acid HCI Hydrochloric acid HBr Hydrobromic acid HI Hydroiodic acid HCN Hydrocyanic acid H2S Hydrosulfuric acid Acid Name HNO3 nitric acid HNO2 Nitrous acid H2SO4 Sulfuric acid H2SO3 Sulfurous acid H3PO4 Phosphoric acid HC2H3O2 Acetic acid

Question # 4: Naming Acids With and Without Oxygen 1. What is NH4SO4?

Writing Formulas from Names It is essential to learn the name, composition, and charge of each of the common polyatomic anions(and the NH4 +cation). You must also learn the names of the common acids. I.E. Calcium hydroxide a.k.a. Ca(OH)2 because you know that calcium forms only Ca2+ ions and that since hydroxide is OH- , 2 of these anions are required to give a neutral compound.

Question # 5: Writing Formulas from Names Practice: Give the formula and at least one comment for the Compounds: Calcium chloride and nitric acid.

Quiz 1.)When a metal is present that forms more than one cation, what is required to specify the cation charge? 2.) How do you name an acid that does not contain oxygen? Which prefix and suffix do you use? 3.) What is the formula for carbon dioxide? 4.) How do you name an acid that has oxygen in it? 5. Give the formula for each of the following compounds: ammonium perchlorate Cobalt(III) nitrate Potassium hydroxide Lead(IV) oxide

Answer Key! PowerPoint Answers: 1.) A. A polyatomic ion containing at least one oxygen atom and one or more atoms of a least one other element. Hydroxide and peroxide. 2.) A. Parentheses are used to enclose the ion and a subscript is written after the closing parentheses. 3.) A. When the anion contains oxygen, the acid name is formed from the root name of the central element of the anion or the anion name, with a suffix of ic or ous. 4. A. Ammonium Sulfate. 5.) Name Formula Comments Nitric acid HNO3 Common strong acid; memorize. Calcium chloride CaCI2 We need two CI- to balance Ca2+; Ca (Group 2) always forms Ca2+. ) Quiz Answers : 1.) A. A Roman numeral is required to specify the cation charge, just as in naming Type II binary ionic compounds. 2. A. Hydro= Prefix. ic=suffix. 3.) A.CO2 4.) A. First, you check your ending of the anion name if it ends with – ite, then add the suffix- ous, if it ends with –ic, then add the suffix –ic. 5.) ammonium perchlorate NH4CIO4 Cobalt(III) nitrate Co(NO3)3 Potassium hydroxide KOH Lead(IV) oxide PbO2

Credits! Pictures:http://z.about.com/d/chemistry/1/0/y/c/hydrochloricacid.jpg - http://www.800mainstreet.com/4/h3po4.GIF - http://www.chemistry.wustl.edu/~edudev/LabTutorials/PeriodicProperties/Ions/images/hphosphate3a.jpg - http://www.rain.org/homeschool/chemistry/img/atom1.jpg- http://www.pmf.ukim.edu.mk/PMF/Chemistry/teachers/DarMar-zz.gif - http://www.dowcorning.com/images/discover/phase_3/building_blocks_molecules/basic-strcuture.jpg - http://images.google.com/imgres?imgurl=http://chemcarling.googlepages.com/figure-01-39.jpg/figure-01-39-full.jpg&imgrefurl=http://chemcarling.googlepages.com/&usg=__5joqx7M8inNTC5x8dfcIwVCCPqs=&h=434&w=525&sz=35&hl=en&start=119&tbnid=LJCda3i6SuiCqM:&tbnh=109&tbnw=132&prev=/images%3Fq%3Dchemistry%2Bnomenclature%26gbv%3D2%26ndsp%3D21%26hl%3Den%26sa%3DN%26start%3D105 Charts: McDougal Littell: World of Chemistry Book. Research and Helpful Information: http://www.shodor.org/UNChem/basic/nomen/index.html - http://antoine.frostburg.edu/chem/senese/101/compounds/polyatomic.shtml