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Chemical Names and Formulas Chapter 9

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Section 1 Naming Ions

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Section 1 Learning Targets 9.1.1 I can identify the charges of monatomic ions by using the periodic table, and name the ions. 9.1.2 I can define a polyatomic ion and write the names and formulas of the most common polyatomic ions. 9.1.3 I can identify the two common endings for the names of most polyatomic ions.

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Monatomic Ions Monatomic ion consist of a single atom with a positive or negative charge resulting from the gain or loss of one or more valence electrons.

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Cations When the metals in Groups 1A, 2A and 3A lose electrons they form cations with positive charges equal to the group number. The names of these ions are the same as the element name with ion after it.

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Anions Nonmetals of Groups 5A, 6A, and 7A gain electrons to form anions with negative charges. The charge of any ion of a Group A nonmetal is determined by subtracting 8 from the group number.

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Group 7A so 7-8=-1; 6A so 6-8=-2; 5A so 5- 8=-3 The names of these ions change. The endings are dropped and replaced by ide ion (sulfur = sulfide ion). Groups 4A and 8A elements do not usually form ions.

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Examples: 1. Name the ions formed by these elements and classify them as anions or cations: a) Selenium ____________________ b) Barium ____________________ c) Phosphorus ____________________

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Examples: 2. Name the following ions: a) I - ____________________ b) N 3- ____________________ c) O 2- ____________________

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This table can be found on page 254

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Ions of Transition Metals The charges of the cations of many transition metal ions must be determined from the number of electrons lost.

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Two methods classical (-ous and ic endings) or the stock system (roman numerals). Preferred is the stock system because the roman numeral tells the charge. So why do we use Roman numerals or the classical method anyway?

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This table can be found on page 255

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Examples: 1. Name the following ions: a) Fe 3+ ____________________ b) Cu + ____________________ c) Mn 4+ ____________________ d) Sn 2+ ____________________ e) Pb 4+ ____________________

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Polyatomic Ions Polyatomic ion composed of more than one atom. The names of most polyatomic anions end in ate or ite. There are very few positive polyatomic ions.

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Examples: 1. Write the symbol or formula (including charge) for each of the following ions: a) Ammonium ion ____________________ b) Chromate ion ____________________ c) Tin (II) ion ____________________ d) Nitrate ion ____________________

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Examples: 2. Name the following ions: a) OH - ____________________ b) Pb 4+ ____________________ c) SO 4 2- ____________________ d) O 2- ____________________

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Section 2 Naming and Writing Formulas for Ionic Compounds

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Section 2 Learning Targets 9.2.1 I can apply the rules for naming and writing formulas for binary ionic compounds. 9.2.2 I can apply the rules for naming and writing formulas for compounds with polyatomic ions.

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Binary Ionic Compounds In the past anyone who created a compound named it. Currently there is a system. Antione Lavoisier decided it was too difficult to memorize unrelated names and formulas.

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Naming Binary Ionic Compounds Binary compound compound of two elements and can be either ionic or molecular. To name binary ionic compounds, place the name of the cation first followed by the anion name.

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Examples: 1. Write the names of the following binary ionic compounds: a) NaCl ____________________ b) MgBr 2 ____________________ c) SrO ____________________ d) Li 2 O ____________________ e) Be 3 N 2 ____________________

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For transition metals you need to figure the charge of the metal and put that in parentheses as a Roman numeral.

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Examples: 1. Write the names of the following binary ionic compounds: a) SnO 2 ____________________ b) Fe 2 O 3 ____________________ c) MnO ____________________ d) MnO 2 ____________________ e) Co 3 N 2 ____________________

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Writing Formulas for Binary Ionic Compounds Write the symbol of the cation and then the anion. Add what ever subscripts are needed to balance the charges.

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Examples: 1. Write the formulas for the compounds formed from these pairs of ions: a) Ba 2+, S 2- ____________________ b) Ca 2+, N 3- ____________________ c) Li +, O 2- ____________________ d) Cu 2+, I - ____________________

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Examples: 2. Write the formulas for these compounds: a) Sodium iodide ____________________ b) Potassium sulfide ____________________ c) Calcium iodide ____________________

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For transition metals the Roman numeral tells the charge on the metal cation. Then the same as before, balance the charges.

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Examples: 1. Write the formulas for the following compounds: a) Tin (IV) nitride ____________________ b) Copper (I) oxide ____________________ c) Copper (II) oxide ____________________ d) Lead (II) sulfide ____________________ e) Iron (III) oxide ____________________

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Compounds with Polyatomic Ions Write the symbol for the cation followed by the formula for the polyatomic ion and balance the charges. HINT: if you need more than one polyatomic ion use parenthesis.

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Examples: 1. Write the formula for the following compounds: a) Ammonium nitride ____________________ b) Ammonium cyanide ___________________ c) Calcium carbonate ____________________ d) Tin (IV) sulfite ____________________ e) Magnesium phosphate __________________

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Naming Compounds with Polyatomic Ions To name a compound containing a polyatomic ion, state the cation first and then the anion, just as you did for binary ionic compounds.

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Examples: 1. Name the following compounds: a) Sn 2 (CO 3 ) 4 ____________________ b) Mg(CN) 2 ____________________ c) Fe(NO 3 ) 3 ____________________ d) (NH 4 ) 3 PO 4 ____________________ e) CuSO 4 ____________________

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Section 3 Naming and Writing Formulas for Molecular Compounds

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Section 3 Learning Targets 9.3.1 I can interpret the prefixes in the names of molecular compounds in terms of their chemical formulas. 9.3.2 I can apply the rules for naming and writing formulas for binary molecular compounds.

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Naming Binary Molecular Compounds Remember binary means 2. Molecular compounds have covalent bonds not ionic like previous sections.

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A prefix in the name of a binary molecular compound tells you how many atoms of each element are present in each molecule of the compound. Ending is still ide so make sure youre telling the difference between molecular and ionic.

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Examples: 1. Write the name for the following binary molecular compounds: a) NCl 3 ____________________ b) SO 3 ____________________ c) NI 3 ____________________ d) N 2 O 3 ____________________ e) N 2 H 4 ____________________

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Writing Formulas for Binary Molecular Compounds Use the prefixes in the name to tell you the subscripts of each element in the formula. Then write the correct symbols for the two elements with the appropriate subscripts.

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Examples: 1. Write the formulas for the following binary molecular compounds: a) Phosphorus pentachloride __________________ b) Iodine heptafluoride ____________________ c) Chlorine trifluoride ____________________ d) Iodine dioxide ____________________ e) Diphosphorus trioxide ____________________

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Section 4 Naming and Writing Formulas for Acids and Bases

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Section 4 Learning Targets 9.4.1 I can apply three rules for naming acids. 9.4.2 I can apply the rules in reverse to write the formulas for acids. 9.4.3 I can apply the rules for naming bases.

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Naming Acids Acid a compound that contains one or more hydrogen atoms and produces hydrogen ions (H + ) when dissolved in water.

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Rules for Naming Acids 1. When the name of the anion (X) ends in ide, the acid name begins with the prefix hydro-. The stem of the anion has the suffix ic and is followed by the word acid. HCl (aq) (X = chloride) is named hydrochloric acid. H 2 S (aq) (X = sulfide) is named hydrosulfuric acid.

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2. When the anion name ends in ite, the acid name is the stem of the anion with the suffix ous, followed by the word acid. H 2 SO 3(aq) (X = sulfite) is named sulfurous acid.

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3. When the anion name ends in ate, the acid name is the stem of the anion with the suffix ic followed by the word acid. HNO 3(aq) (X = nitrate) is named nitric acid.

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Examples: 1. Write the names for the following acids: a) HNO 2 ____________________ b) HCN ____________________ c) HMnO 4 ____________________ d) H 2 S ____________________ e) HClO 4 ____________________

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Writing Formulas for Acids Use the rules for writing the names of acids in reverse to write the formulas for acids.

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Examples: 1. Write the formulas for the following acids: a) Carbonic acid ____________________ b) Sulfurous acid ____________________ c) Hydroiodic acid ____________________ d) Nitrous acid ____________________ e) Phosphoric acid ____________________

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Names and Formulas for Bases Base an ionic compound that produces hydroxide ions (OH - ) when dissolved in water. Bases are named in the same way as other ionic compounds. The name of the cation is followed by the name of the anion. Formulas are written the same as for ionic compounds.

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Examples: 1. Identify each compound as an acid or a base: a) Ba(OH) 2 ____________________ b) HClO 4 ____________________ c) Fe(OH) 3 ____________________ d) KOH ____________________

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Examples: 2. Write the names for the following bases: a) Ba(OH) 2 ____________________ b) LiOH ____________________ c) Pb(OH) 2 ____________________ d) Mg(OH) 2 ____________________ e) Al(OH) 3 ____________________

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Section 5 The Laws Governing Formulas and Names

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Section 5 Learning Targets 9.5.1 I can define the laws of definite proportions and multiple proportions. 9.5.2 I can apply the rules for naming chemical compounds by using a flowchart. 9.5.3 I can apply the rules for writing the formulas of chemical compounds by using a flowchart.

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The Laws of Definite and Multiple Proportions The rules for naming and writing formulas are possible because compounds form from the elements in predictable ways. These ways are summed up in two laws: the law of definite proportions and the law of multiple proportions.

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The Law of Definite Proportions States that in samples of any chemical compound, the masses of the elements are always in the same proportions.

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The Law of Multiple Proportions States whenever the same two elements form more than one compound, the different masses of one element that combine with the same mass of the other element are in the ratio of small whole numbers.

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Practicing Skills: Naming Chemical Compounds Follow the arrows and answer the questions on the flow chart to write the correct name for a compound.

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Examples: 1. Write the names for the following compounds: a) NaClO 3 ____________________ b) HClO 4 ____________________ c) KHSO 4 ____________________ d) Cl 2 O ___________________

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Examples: 1. Write the names for the following compounds: e) SnO 2 ____________________ f) Ca(OH) 2 ____________________ g) K 2 CrO 4 ____________________ h) Fe(C 2 H 3 O 2 ) 3 ____________________ i) SiCl 4 ____________________

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Practicing Skills: Writing Chemical Formulas An ide ending generally indicates a binary compound. Either ionic or covalent. An ite or ate ending means a polyatomic ion that includes oxygen is in the formula. An ic or ous ending shows that the compound may be an acid.

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Practicing Skills: Writing Chemical Formulas Prefix in a name generally indicate the compound is molecular. A Roman numeral after the name of a cation shows the ionic charge of the cation.

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Examples: 1. Write the formulas for the following compounds: a) Calcium bromide ____________________ b) Aluminum carbide ___________________ c) Tin (IV) cyanide ____________________ d) Strontium acetate ____________________ e) Silver chloride ____________________

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Examples: 1. Write the formulas for the following compounds: f) Nitrogen dioxide ____________________ g) Lithium hydride ____________________ h) Sodium silicate ____________________ i) Acetic acid ____________________ j) Hydrochloric acid ___________________