Naming Compounds and Writing Formulas Metals and Nonmetals For nomenclature purposes, metals are to the left of the stair step line and nonmetals are to the right. Systematic Naming A compound is made of two or more elements. The name should tell us how many and what type of atoms. Types of Compounds The types of compounds you will learn how to name and draw are ionic compounds (binary and ternary), molecular compounds and acids (binary and ternary). Atoms and Ions Atoms are electrically neutral. They have the same number of protons and electrons. Ions are atoms, or groups of atoms, with a charge. Ions have a different numbers of electrons. Anions negative ion. An anion is a _________ gained electrons. An anion has _______ Nonmetals can gain electrons. The charge is written as a superscript on the right. 1F 2O 1 electron(s) Has gained ___ 2 electron(s) Has gained ___ Cations positive ion. A cation is a _________ It is formed by _______ losing electrons. There are more protons than electrons. Metals form cations. 1+ 1 electron(s) K Has lost ___ 2+ 2 electron(s) Has lost ___ Ca Oxidation Numbers IONIC COMPOUNDS Naming Cations For cations, if the charge is always the same (Group A) just write the name of the metal. Naming Cations Li1+ lithium Li is the symbol for ________. Lithium is a Group 1A metal, so the charge is always the same. Write the name of the metal. Li1+ is called the ___________. lithium ion Naming Cations Sr2+ strontium Sr is the symbol for __________. Strontium is a Group 2A metal, so the charge is always the same. Write the name of the metal. Sr2+ is called the _____________. strontium ion Naming Cations Transition metals (as well as tin and lead) can have more than one type of charge. Indicate the charge with Roman numerals in parenthesis. Zinc (Zn2+) and silver (Ag1+), although transition metals, only have one possible charge. Roman numerals ARE NOT used for zinc and silver. Naming Cations Fe2+ Fe is the symbol for ______. iron Iron is a transition metal, so the charge is not always the same. Write the name of the metal, indicating the charge with Roman numerals in parenthesis. Fe2+ is called the ___________. iron (II) ion Naming Cations Pb2+ Pb is the symbol for ______. lead Lead is a Group 4A metal, and the charge is not always the same. Write the name of the metal, indicating the charge with Roman numerals in parenthesis. Pb2+ is called the ___________. lead (II) ion Problem 1) Name the following cations. a) Ca2+ Calcium ion b) Al3+ Aluminum ion c) Sn4+ Tin (IV) ion Problem Name the following ions. d) Na1+ Sodium ion e) Fe3+ Iron (III) ion f) Cu1+ Copper (I) ion Naming Anions Naming monatomic anions is always the same. Change the element ending to – ide Example: F1 F is the symbol for fluorine, F1- is called fluor ine. ide. Naming Anions Cl Cl is the symbol for _________. chlorine Chlorine is a Group 7A nonmetal, so the charge is always the same (-1). Cl- is called the ____________. chloride ion Naming Anions O2 O is the symbol for _________. oxygen Oxygen is a Group 6A nonmetal, so the charge is always the same (-2). O2- is called the __________. oxide ion Problem 2) Name the following anions. a) S2- sulfide ion b) Br - bromide ion Problem 2) Name the following anions. c) N3d) Se2- nitride ion selenide ion Ionic Compounds In the formula for an ionic compound, the symbol of the cation is written before that of the anion. Subscripts, or small numbers written to the lower right of the chemical symbols, show the numbers of ions of each type present in a formula unit. Naming Binary Ionic Compounds Binary ionic compounds are composed of a metal bonded with a nonmetal. Name the metal ion using a Roman numeral in parenthesis if necessary. Follow this name with the name of the nonmetal ion. Problem 3) Name the following binary ionic compounds. a) NaCl sodium chloride b) Ca3P2 calcium phosphide Problem Name the following binary ionic compounds. c) CuO d) SnBr2 Copper (II) oxide Tin (II) bromide Problem Name the following binary ionic compounds. e) Fe2S3 f) AlF3 Iron (III) sulfide Aluminum fluoride Problem Name the following binary ionic compounds. g) KCl Potassium chloride h) Na3N Sodium nitride Problem Name the following binary ionic compounds. i) CrN Chromium (III) nitride j) PbO2 Lead (IV) oxide Writing Formulas for Cations Write the formula for the metal. If a Roman numeral is in parenthesis use that number for the charge. Indicate the charge with a superscript. If no Roman numeral is given, find the Group A metal on the periodic table and determine the charge from the column number. Writing Formulas for Cations Nickel (II) ion ____ Ni is the symbol for nickel. Nickel is a transition metal, which is the reason why the charge with Roman numerals in parenthesis was included. The formula for the nickel (II) ion is Ni2+ _____. Writing Formulas for Cations Gallium ion ____ Ga is the symbol for gallium. Gallium is a Group 3A metal and its charge is always the same (+3). The formula for the gallium ion is Ga3+ ______. Problem 4) Write the formulas for the following cations. a) Magnesium ion Mg2+ b) Copper (II) ion c) Potassium ion Cu2+ 1+ K Problem Write the formulas for the following ions. d) Silver ion Ag1+ e) Chromium (VI) ion f) Mercury (II) ion 6+ Cr Hg2+ Writing Formulas for Anions Write the formula for the nonmetal. Find the Group A nonmetal on the periodic table and determine the charge from the column number. Writing Formulas for Anions Phosphide ___ P is the symbol for phosphorus. Looking at the periodic table and finding phosphorus, the oxidation number (charge) can be determined. The formula for phosphide is _____. P3- Writing Formulas for Anions Bromide ___ Br is the symbol for bromine. Looking at the periodic table and finding bromine, the oxidation number (charge) can be determined. The formula for bromide is _____. Br1- Problem 5) Write the formulas for the following anions. As3a) arsenide b) telluride 2Te Problem Write the formulas for the following anions. 1c) iodide ion I d) carbide ion C4- Writing Formulas for Ionic Compounds Oxidation numbers can be used to determine the chemical formulas for ionic compounds. If the oxidation number of each ion is multiplied by the number of that ion present in a formula unit, and then the results are added, the sum must be zero. Writing Formulas for Binary Ionic Compounds Write the symbol for the metal. Determine the oxidation number from either the column number or the Roman numeral and write it as a superscript to the right of the metal’s symbol. Writing Formulas for Binary Ionic Compounds To the right of the metal’s symbol, write the symbol for the nonmetal. Determine the oxidation number from the column number and write it as a superscript to the right of the nonmetal’s symbol. Writing Formulas for Binary Ionic Compounds Example: potassium fluoride K + F - Writing Formulas for Binary Ionic Compounds If the two oxidation numbers add together to get zero, the formula is a one-to-one ratio of the elements. Writing Formulas for Binary Ionic Compounds Example: potassium fluoride + KKFF - Writing Formulas for Binary Ionic Compounds Example: aluminum sulfide Al 3+ S 2- Writing Formulas for Binary Ionic Compounds If the two oxidation numbers DO NOT add together to get zero, you will need to “criss-cross” the superscripts. These numbers now become subscripts. Writing Formulas for Binary Ionic Compounds Example: aluminum sulfide 3+ 2- Al 2- S 3+ Writing Formulas for Binary Ionic Compounds Omit all positive and negative signs and omit all 1’s. Writing Formulas for Binary Ionic Compounds Example: aluminum sulfide AlAl2 2SS3 3 Problem 6) Write the formulas for the following binary ionic compounds. a) Lithium selenide b) Tin (II) oxide Li2Se SnO Problem Write the formulas for the following binary ionic compounds. c) Tin (IV) oxide SnO2 d) Magnesium fluoride MgF2 Problem Write the formulas for the following binary ionic compounds. e) Copper (II) sulfide CuS f) Iron (II) phosphide Fe3P2 Problem Write the formulas for the following binary ionic compounds. g) Gallium nitride GaN h) Iron (III) sulfide Fe2S3 Naming Ternary Ionic Compounds Ternary ionic compounds are composed of at least 3 elements. Name the metal ion, using a Roman numeral in parenthesis if necessary. Follow this name with the name of the polyatomic ion. Polyatomic ions Polyatomic ions are groups of atoms that stay together and have a charge. Examples are on page 7 of the Reference Tables for Chemistry and include: Nitrate NO3 Nitrite NO2 Hydroxide OH Ternary Ionic Compounds There is one polyatomic ion with a positive oxidation number (NH4+) that may come first in a compound. Name the ion, ammonium. Follow this name with the name of the anion or second polyatomic ion. Examples 7) Name the following ternary ionic compounds. a) LiCN Lithium cyanide b) Fe(OH)3 Iron (III) hydroxide Examples Name the following ternary ionic compounds. c) (NH4)2CO3 Ammonium carbonate d) NiPO4 Nickel (III) phosphate Problems Name the following ternary ionic compounds. Sodium nitrate e) NaNO3 f) CaSO4 Calcium sulfate Problems Name the following ternary ionic compounds. g) (NH4)2O Ammonium oxide h) CuSO3 Copper (II) sulfite Writing Formulas for Ternary Ionic Compounds Write the symbol for the metal or ammonium ion. Write the oxidation number as a superscript to the right of the metal’s/ammonium ion’s symbol. Writing Formulas for Ternary Ionic Compounds To the right of the metal’s symbol, write the symbol for the nonmetal or polyatomic ion. Write the oxidation number as a superscript to the right of the nonmetal’s/polyatomic ion’s symbol. Writing Formulas for Ternary Ionic Compounds Example: potassium nitrate K + NO3 - Writing Formulas for Ternary Ionic Compounds If the two oxidation numbers add together to get zero, the formula is a one-to-one ratio of the elements. Writing Formulas for Ternary Ionic Compounds Example: potassium nitrate + - KKNO NO 33 Writing Formulas for Ternary Ionic Compounds Example: aluminum hydrogen sulfate Al 3+ HSO4 - Writing Formulas for Ternary Ionic Compounds If the two oxidation numbers DO NOT add together to get zero, you will need to “criss-cross” the superscripts. These numbers now become subscripts. Parentheses are to be placed around polyatomic ions before criss-crossing. Writing Formulas for Ternary Ionic Compounds Example: aluminum hydrogen sulfate 3+ - Al - (HSO4) 3+ Writing Formulas for Ternary Ionic Compounds Omit all positive and negative signs and omit all 1’s. Writing Formulas for Ternary Ionic Compounds Example: aluminum hydrogen sulfate Al Al(HSO (HSO4)33 Problems 8) Write the formulas for the following ternary ionic compounds. a) Ammonium chloride NH Cl 4 b) Ammonium sulfide (NH4)2S Problems Write the formulas for the following ternary ionic compounds. c) Barium nitrate Ba(NO ) 3 2 d) Zinc iodate Zn(IO3)2 Problems Write the formulas for the following ternary ionic compounds. e) Sodium hypochlorite NaClO f) Chromium (III) acetate Cr(CH3COO)3 or Cr(C2H3O2)3 Problems Write the formulas for the following ternary ionic compounds. g) Iron (II) dichromate FeCr O 2 h) Mercury (I) bromate HgBrO3 7 STOP HERE COVALENT (Molecular) COMPOUNDS Molecular Compounds Molecular compounds are made of molecules. They are made by joining nonmetal atoms together into molecules. Naming is Easier A molecular compound’s name tells you the number of atoms through the use of prefixes. Prefixes 1 mono 2 di 3 tri 4 tetra 5 penta 6 hexa 7 hepta 8 octa 9 nona 10 deca Prefixes The name will consist of two words. Prefix name prefix name -ide One exception is we don’t write mono- if there is only one of the first element. Prefixes The following double vowels cannot be used when writing names: (oa) (oo) Example NO2 There is one nitrogen mononitrogen But, you cannot use mono- on the first element, so drop the prefix. nitrogen mononitrogen Example NO2 There are two oxygens dioxygen Example NO2 dioxygen You need the suffix -ide diox ygen ide Example NO2 nitrogen dioxide Example N2O There are two nitrogens dinitrogen There is one oxygen monooxygen Example N2O monooxygen You cannot run (oo) together, so monoxygen Example N2O monoxygen You need the suffix -ide monoxygen ide Example N2O dinitrogen monoxide Problem 9) Name the following molecular compounds. a) Cl2O7 b) CBr4 dichlorine heptoxide carbon tetrabromide Problem Name the following molecular compounds. c) CO2 carbon dioxide d) BCl3 boron trichloride Naming Molecular Compounds You will not need to criss-cross oxidation numbers. Molecular compounds name tells you the number of atoms through the use of prefixes. Example diphosphorus pentoxide The name implies there are 2 phosphorous atoms and 5 oxygens. P2O5 Example sulfur hexaflouride The name implies there is 1 sulfur atom and 6 fluorines. SF6 Problem 10) Write the formulas for the following molecules. a) tetraiodine nonoxide I O 4 9 b) nitrogen trioxide NO3 Problem Write the formulas for the following molecules. c) carbon tetrahydride CH 4 d) phosphorus trifluoride PF3 Types of Compounds Smallest piece Types of elements State Melting Point Ionic Molecular Formula Unit Molecule Metal and nonmetal Nonmetals Solid Solid, liquid or gas High >300ºC Low <300ºC Acids Writing Names and Formulas Acids Acids are compounds that give off hydrogen ions (H+) when dissolved in water. Acids will always contain one or more hydrogen ions next to an anion. The anion determines the name of the acid. Naming Binary Acids Binary acids contain hydrogen and an anion whose name ends in –ide. When naming the acid, put the prefix hydro- and change -ide to -ic acid. Example HCl The acid contains the hydrogen ion and chloride ion. Begin with the prefix hydro-, name the nonmetallic ion and change -ide to -ic acid. hydrochloride ic acid Example H2S The acid contains the hydrogen ion and sulfide ion. Begin with the prefix hydro- and name the nonmetallic ion. hydrosulfide Example H2S The next step is change -ide to -ic acid, but for sulfur the “ur” is added before -ic. hydrosulfide ur ic acid Problem 11. Name the following binary acids. a) HF (hydrofluoric acid) b) H3P (hydrophosphoric acid) Writing the Formulas for Binary Acids The prefix hydro- lets you know the acid is binary. Determine whether you need to crisscross the oxidation numbers of hydrogen and the nonmetal. Example Hydrobromic acid The acid contains the hydrogen ion and the bromide ion. Example Hydrobromic acid 1+ 1H Br The two oxidation numbers add together to get zero. HBr Example Hydrotelluric acid The prefix hydro- lets you know the acid is binary. The acid contains the hydrogen ion and the telluride ion. Example Hydrotelluric acid 1+ 2H Te The two oxidation numbers do NOT add together to get zero, so you must criss-cross. H2Te Problem 12) Write the formulas for the following binary acids. a) Hydrocyanic acid HCN b) Hydroselenic acid H2Se Naming Ternary Acids The acid is a ternary acid if the anion has oxygen in it. The anion ends in -ate or -ite. Change the suffix -ate to -ic acid Change the suffix -ite to -ous acid The hydro- prefix is NOT used! Example HNO3 The acid contains the hydrogen ion and nitrate ion. Name the polyatomic ion and change -ate to -ic acid. nitrate ic acid Example HNO2 The acid contains the hydrogen ion and nitrite ion. Name the polyatomic ion and change -ite to -ous acid. nitrite ous acid Example H3PO4 The acid contains the hydrogen ion and phosphate ion. Name the polyatomic ion and change -ate to -ic acid. phosphate oric acid Problem 13) Name the following ternary acids. a) H2CO3 (carbonic acid) b) H2SO4 (sulfuric acid) Problem Name the following ternary acids. c) H2CrO4 d) HClO2 (chromic acid) (chlorous acid) Writing the Formulas for Ternary Acids The lack of the prefix hydro- from the name implies the acid is ternary, made of the hydrogen ion and a polyatomic ion. Determine whether you need to crisscross the oxidation numbers of hydrogen and the polyatomic ion. Example Acetic acid The polyatomic ion must end in –ate since the acid ends in -ic. The acid is made of H+ and the acetate ion. 1+ H C 1H O 2 3 2 Example 1+ H C 1H O 2 3 2 The two charges when added equal zero. HC2H3O2 Example Sulfurous acid Again the lack of the prefix hydroimplies the acid is ternary, made of the hydrogen ion and a polyatomic ion. Example sulfurous acid The polyatomic ion must end in –ite since the acid ends in -ous. The acid is made of H+ and the sulfite ion. 1+ 2H SO3 Example 1+ 2H SO3 The two charges when added do not equal zero, so you must crisscross the oxidation numbers. Example 1+ 2H SO3 Ignore the negative sign and ones are understood. H2SO3 Problem 14) Write the formulas for the following ternary acids. a) perchloric acid HClO 4 b) iodic acid HIO3 Problem Write the formulas for the following ternary acids. c) dichromic acid H Cr O 2 d) hypochlorous acid 2 7 HClO