Chemical Nomenclature Chapter 2.5-8

Chemical Nomenclature Chapter 2.5-8 Octet Rule An octet is 8 valence electrons is associated with the stability of the noble gases does not occur with He, which is stable with two valence electrons (duet) Valence electrons He 1s 2 2 Ne 1s 2 2s 2 2p 6 8 Ar 1s 2 2s 2 2p 6 3s 2 3p 6 8 Kr 1s 2 2s 2 2p 6 3s 2 3p 6 4s 2 3d 10 4p 6 8 2 Forming Octets Atoms acquire octets to become more stable by losing, gaining, or sharing valence electrons by forming ionic or covalent bonds Ionic and Covalent Bonds Ionic bonds involve loss of electrons by a metal gain of electrons by a nonmetal Covalent bonds involve a sharing of electrons 3 4 Positive Ions: Loss of Electrons Ions, which have electrical charges, form when atoms lose or gain electrons to form a stable electron configuration. Positive Ions: Loss of Electrons A sodium atom (Na) will lose its 3s 1 electron to form a sodium ion (Na + ). Because the ionization energies of metals in Groups 1A (1), 2A (2), and 3A (13) are low, metal atoms lose their valence electrons, forming ions with a positive charge. Positively charged ions of metals are called cations. 1

Positive Ions: Loss of Electrons Magnesium, a metal in Group 2A (2), obtains a stable electron configuration by losing two valence electrons, forming an ion with a 2+ charge. Metals Form Positive Ions Metals form positive ions by a loss of their valence electrons with the electron configuration of their nearest noble gas that have fewer electrons than protons. Group 1A (1) metals ion + Group 2A (2) metals ion 2+ Group 3A (13) metals ion 3+ 8 Select the correct answer for aluminum. A. The number of valence electrons is. 1) 1 e 2) 2 e 3) 3 e B. The electron change for the octet is. 1) loss of 3 e 2) gain of 3 e 3) gain of 5 e C. The ionic charge of the aluminum ion is. 1) 3 2) 5 3) 3 + D. The symbol for the aluminum ion is. 1) Al 3+ 2) Al 3-3) Al + Negative Ions: Gain of Electrons The ionization energy of a nonmetal atom in Groups 5A (15), 6A (16), and 7A (17) is high. Rather than lose electrons to form ions, a nonmetal atom will gain one or more electrons to obtain a stable electron configuration. 9 Negative Ions: Gain of Electrons Formation of Negative Ions An atom of chlorine with seven valence electrons gains one electron to form an octet. Because it now has 18 electrons and not 17 electrons, it becomes a chloride ion (Cl ) with a charge of 1. In ionic compounds, nonmetals achieve an octet arrangement gain electrons form negatively charged ions with 3, 2, or 1 charges Negatively charged ions of nonmetals are called anions. 12 2

Select the correct answer for sulfur. A. The group number for sulfur is. B. The number of valence electrons in sulfur is. 1) 4 e 2) 6 e 3) 8e - C. The change in electrons for an octet requires a 1) loss of 2 e 2) gain of 2 e 3) gain of 4 e D. The ionic charge of a sulfide ion is. 1) 2+ 2) 2 3) 4 Ionic Compounds Ionic compounds consist of positive and negative ions. Ions are held together by the strong electrical attraction between opposite charges, called an ionic bond. Noble gases have a stable electron configuration and do not form ionic compounds. 13 Properties of Ionic Compounds Figure 6.1 The elements sodium and chlorine react to form the ionic compound sodium chloride, the compound that makes up table salt. The magnification of NaCl crystals shows the arrangement of Na + ions and Cl ions in a crystal of NaCl. Ionic Compounds Ionic compounds consist of positive and negative ions have high melting and boiling points are solids at room temperature 16 Ionic Formulas An ionic formula consists of positively and negatively charged ions is neutral has charge balance (net charge of zero) total positive charge = total negative charge uses subscripts to indicate the number of ions needed to give charge balance Charge Balance for NaCl, Salt In NaCl, a Na atom loses its valence electron a Cl atom gains an electron the symbol of the metal is written first followed by the symbol of the nonmetal the charges of the ions in the compound are not shown 17 18 3

Charge Balance in NaF The formulas of ionic compounds are determined from the charges on the ions. atoms ions Na + F : Na + : F : NaF sodium fluorine sodium fluoride The overall charge of NaF is zero (0). Na + F = NaF 1(1+ ) + 1(1 ) = 0 Charge Balance In MgCl 2 In MgCl 2 a Mg atom loses two valence electrons two Cl atoms each gain one electron subscripts indicate the number of ions needed to give charge balance 19 20 Charge Balance In Na 2 S In Na 2 S, two Na atoms lose one valence electron each one S atom gains two electrons subscripts show the number of ions needed to give charge balance Writing Ionic Formulas from Charges Charge balance is used to write the formula for sodium nitride, a compound containing Na + and N 3. Na + 3 Na + + N 3 = Na 3 N Na + 3(+1) + 1(3 ) = 0 21 22 Formula from Ionic Charges Write the ionic formula of the compound containing Ba 2+ and Cl. Write the symbols of the ions. Ba 2+ Cl Balance the charges. Ba 2+ Cl Cl two Cl needed Write the ionic formula using a subscript 2 for two chloride ions that give charge balance. Select the correct formula for each of the following ionic compounds: A. Li + and O 2 1) LiO 2) Li 2 O 3) LiO 2 B. Al 3+ and Cl 1) AlCl 3 2) AlCl 3) Al 3 Cl C. Mg 2+ and N 3 1) MgN 2) Mg 2 N 3 3) Mg 3 N 2 BaCl 2 23 24 4

Naming of Ionic Compounds In the name of an ionic compound, the positive ion (first ion) is named as the element the negative ion (second ion) is named by changing the end of the element name to ide Complete the names of the following ions: Ba 2+ Al 3+ K + N 3 O 2 F P 3 S 2 Cl 25 26 Examples of Ionic Compounds with Two Elements Some Ionic Compounds Formula Ions Name Cation Anion NaCl Na + Cl sodium chloride K 2 S K + S 2 potassium sulfide MgO Mg 2+ O 2 magnesium oxide CaI 2 Ca 2+ I calcium iodide Al 2 O 3 Al 3+ O 2 aluminum oxide 27 28 Write the formulas and names for compounds of the following ions: Na + Al 3+ Br S 2 N 3 Write the names of each of the following compounds: 1) CaO 2) KBr 3) Al 2 O 3 4) MgCl 2 29 30 5

Transition Metals That Form Two or More Positive Ions Most transition metals and Group 4 (14) metals form two or more positive ions Zn 2+, Ag +, and Cd 2+ form only one ion Examples: Copper forms Cu + and Cu 2+ Iron forms Fe 2+ and Fe 3+ Gold forms Au + and Au 3+ Metals with Variable Charge 31 32 Examples of Names of Compounds with Variable Charge Metals Transition metals with two different ions use a Roman numeral after the name of the metal to indicate the ionic charge only zinc, silver, and cadmium do not use a Roman numeral because they form only one ion (Zn 2+, Ag +, and Cd 2+ ) Naming FeCl 2 STEP1 Determine the charge of the cation from the anion. Fe (?) + 2Cl = Fe (?) + 2(1 ) = 0 Fe (?) = 2+ = Fe 2+ STEP 2 Name the cation by its element name and use a Roman numeral in parentheses for the charge. Fe 2+ = iron(ii) 33 34 Naming FeCl 2 (continued) STEP 3 Name the anion by using the first syllable of its element name followed by ide. chloride STEP 4 Write the name of the cation first and the name of the anion second. iron(ii) chloride = FeCl 2 Naming Cr 2 O 3 STEP1 Determine the charge of the cation from the anion. 2Cr(?) + 3O 2 = 2Cr (?) + 3(2 ) = 0 2Cr(?) = 6+ Cr(?) = 3+ = Cr 3+ STEP 2 Name the cation by its element name and use a Roman numeral in parentheses for the charge. Cr 3+ = chromium(iii) 35 36 6

Naming FeCl 2 (continued) STEP 3 Name the anion by using the first syllable of its element name followed by ide. oxide STEP 4 Write the name of the cation first and the name of the anion second. chromium(iii) oxide Select the correct name for each. A. Fe 2 S 3 1) iron sulfide 2) iron(ii) sulfide 3) iron (III) sulfide B. CuO 1) copper oxide 2) copper(i) oxide 3) copper (II) oxide 37 38 Writing Formulas Write the formula of potassium sulfide. STEP1 STEP 2 STEP 3 Identify the cation and anion. potassium = K + sulfide = S 2 Balance the charges. K + K + S 2 2(1+) + 2(1 ) = 0 Write the formula, cation first, using the subscripts from the charge balance. 2 K + and 1 S 2 = K 2 S Writing Formulas Write the formula of cobalt(iii) chloride. STEP1 STEP 2 STEP 3 Identify the cation and anion. cobalt (III) = Co 3+ (III = charge of 3+) chloride = Cl Balance the charges. Co 3+ and 3Cl = (3+) + 3(1-) = 0 Write the formula, cation first, using the subscripts from the charge balance. 1 Co 3+ and 3 Cl = CoCl 3 39 40 Polyatomic Ions Select the correct formula for each of the following: A. copper (I) nitride 1) CuN 2) CuN 3 3) Cu 3 N B. lead (IV) oxide 1) PbO 2 2) PbO 3) Pb 2 O 4 A polyatomic ion is a group of atoms has an overall ionic charge Examples: NH 4 + ammonium OH hydroxide NO 3 nitrate NO 2 nitrite CO 2 3 carbonate PO 3 4 phosphate HCO 3 hydrogen carbonate (bicarbonate) 41 42 7

Some Compounds Containing Polyatomic Ions Names and Formulas of Common Polyatomic Ions 43 44 More Names of Polyatomic Ions The names of the common polyatomic anions end in ate NO 3 nitrate PO 4 3 phosphate with one oxygen less end in ite NO 2 nitrite PO 3 3 phosphite with hydrogen use prefix hydrogen (or bi) HCO 3 HSO 3 hydrogen carbonate (bicarbonate) hydrogen sulfite (bisulfite) Prefixes for Names of Polyatomic Ions of Halogens Some polyatomic ions of the halogens require prefixes. ClO 4 perchlorate one oxygen more ClO 3 chlorate most common form ClO 2 chlorite one oxygen less ClO hypochlorite two oxygens less 45 46 Examples of Naming Compounds with Polyatomic Ions In a compound with a negatively charged polyatomic, the positive ion is named first followed by the name of the polyatomic ion NaNO 3 K 2 SO 4 Fe(HCO 3 ) 3 (NH 4 ) 3 PO 3 sodium nitrate potassium sulfate iron(iii) bicarbonate or iron(iii) hydrogen carbonate ammonium phosphite Select the correct formula for each: A. aluminum nitrate 1) AlNO 3 2) Al(NO) 3 3) Al(NO 3 ) 3 B. copper(ii) nitrate 1) CuNO 3 2) Cu(NO 3 ) 2 3) Cu 2 (NO 3 ) C. iron (III) hydroxide 1) FeOH 2) Fe 3 OH 3) Fe(OH) 3 D. tin(iv) hydroxide 1) Sn(OH) 4 2) Sn(OH) 2 3) Sn 4 (OH) 47 48 8

Match each formula with the correct name: A. MgS 1) magnesium sulfite MgSO 3 MgSO 4 2) magnesium sulfate 3) magnesium sulfide B. Ca(ClO 3 ) 2 1) calcium chlorate Ca(ClO) 2 Ca(ClO 2 ) 2 2) calcium chlorite 3) calcium hypochlorite Name each of the following compounds: A. Mg(NO 3 ) 2 B. Cu(ClO 3 ) 2 C. PbO 2 D. Fe 2 (SO 4 ) 3 E. Ba 3 (PO 3 ) 2 49 50 Writing Formulas with Polyatomic Ions The formula of an ionic compound containing a polyatomic ion must have a charge balance that equals zero(0) Na + and NO 3 NaNO 3 with two or more polyatomic ions encloses the polyatomic ions in parentheses Write the correct formula for each: A. potassium bromate B. calcium carbonate C. sodium phosphate D. iron(iii) oxide E. iron (II) nitrite Mg 2+ and 2NO 3 Mg(NO 3 ) 2 subscript 2 for charge balance 51 52 Name the following compounds: A. Ca 3 (PO 4 ) 2 B. FeBr 3 C. Al 2 S 3 D. Mn(NO 2 ) 2 E. NaHCO 3 Write the formulas for the following: A. calcium nitrate B. iron(ii) hydroxide C. aluminum carbonate D. copper(ii) hypobromite E. lithium phosphate 53 54 9

Molecular Compounds A molecular compound contains two or more nonmetals that form a covalent bond. Valence electrons are shared by nonmetal atoms in a covalent bond to achieve stability. When two or more atoms share electrons, they form a molecule. H 2, A Covalent Molecule In a hydrogen (H 2 ) molecule, two hydrogen atoms share electrons to form a covalent single bond each H atom acquires two (2) electrons each H becomes stable like helium (He) 56 Diatomic Elements These elements share electrons to form diatomic, covalent molecules. What is the name of each of the following diatomic molecules? H 2 N 2 Cl 2 O 2 I 2 57 58 Names of Covalent Compounds Prefixes are used in the names of covalent compounds because two nonmetals can form two or more different compounds Examples of compounds of N and O: NO nitrogen oxide NO 2 nitrogen dioxide N 2 O dinitrogen oxide N 2 O 4 dinitrogen tetroxide N 2 O 5 dinitrogen pentoxide Naming Molecular Compounds List atoms in order of increasing electronegativity Use prefixes to denote the number of atoms in the molecule. (mono-, di-, etc ) The last atom is given an ide suffix Drop o or a from prefix for atoms beginning with a Molecular Prefixes: vowel 1 mono- 7 hepta- 2 di- 8 octa- Omit the prefix mono- when 3 tri- 9 nonathere is only one of the first (least electronegative) atom. 4 tetra- 10 deca- Mono- is sometimes omitted 5 penta- 11 undecafrom the second atom in diatomic molecules. 6 hexa- 12 dodeca- 59 10

Select the correct name for each compound. A. SiCl 4 1) silicon chloride 2) tetrasilicon chloride 3) silicon tetrachloride B. P 2 O 5 1) phosphorus oxide 2) phosphorus pentoxide 3) diphosphorus pentoxide C. Cl 2 O 7 1) dichlorine heptoxide 2) dichlorine oxide 3) chlorine heptoxide Write the name of each covalent compound: CO CO 2 PCl 3 CCl 4 N 2 O 61 62 Write the correct formula for each of the following: A. phosphorus pentachloride Identify each compound as ionic or covalent and give its correct name. A. SO 3 B. MnCl 2 B. dinitrogen trioxide C. (NH 4 ) 3 PO 4 D. Cu 2 CO 3 C. sulfur hexafluoride E. N 2 O 4 63 64 Identify each compound as ionic or covalent and give its correct name. A. Ca 3 (PO 4 ) 2 B. FeBr 3 C. SCl 2 D. Cl 2 O Name each of the following ionic or molecular compounds. A. BF 3 B. OCl 2 C. Al 2 O 3 D. Ni 3 PO 4 65 11

Acids Some Acids and Their Anions Arrhenius acids produce H + ions in water H 2 O HCl(g) H + (aq) + Cl (aq) are electrolytes have a sour taste turn litmus red neutralize bases 67 68 Names of Acids Acids that produce H + and a simple nonmetal ion in water are named with the prefix hydro and end with ic acid. HCl hydrochloric acid HBr hydrobromic acid The acid HCN that produces H + and the simple polyatomic ion CN is also named with hydro. HCN hydrocyanic acid Oxyacids of Nitrogen and Sulfur Nitrogen and sulfur each form two oxyacids (acids with polyatomic atoms with oxygen) that are named by changing the end of the polyatomic ion ate to ic acid (common form) polyatomic ion ite to ous acid NO 3 nitrate ion HNO 3 nitric acid NO 2 nitrite ion HNO 2 nitrous acid SO 2 4 sulfate ion H 2 SO 4 sulfuric acid SO 2 3 sulfite ion H 2 SO 3 sulfurous acid 69 70 Acids of Halogens with Oxygen Two oxyacids of the halogens in Group 7A(17) are named by changing the end of the common form of ate to ic acid (common form) ClO 3 chlorate ion HClO 3 chloric acid of ite to ous acid ClO 2 chlorite ion HClO 2 chlorous acid Prefixes of Oxyacids of Halogens Two other oxyacids of halogen use prefixes. An acid with one oxygen more than the ic acid is named with the prefix per HClO 3 chloric acid HClO 4 perchloric acid An acid with one oxygen less than the ous acid is named with the prefix hypo HClO 2 chlorous acid HClO hypochlorous acid 71 72 12

Select the correct name for each. A. HBr 1) bromic acid 2) bromous acid 3) hydrobromic acid B. H 2 CO 3 1) carbonic acid 2) hydrocarbonic acid 3) carbonous acid C. HBrO 1) hypobromic acid 2) hypobromous acid 3) bromous acid Bases Arrhenius bases produce OH ions in water taste bitter or chalky are electrolytes feel soapy and slippery neutralize acids 73 74 Some Common Bases A base with OH ions is named as the hydroxide of the metal in the formula. NaOH KOH Ba(OH) 2 Al(OH) 3 Fe(OH) 3 sodium hydroxide potassium hydroxide barium hydroxide aluminum hydroxide iron (III) hydroxide Match each of the following formulas with its correct name: A. HNO 2 1) periodic acid B. Ca(OH) 2 2) sulfuric acid C. H 2 SO 4 3) sodium hydroxide D. HIO 4 4) nitrous acid E. NaOH 5) calcium hydroxide 75 76 Identify each of the following as a characteristic of an A) acid or B) base. 1. has a sour taste 2. produces OH in aqueous solutions 3. has a chalky taste 4. is an electrolyte 5. produces H + in aqueous solutions 77 13