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Intro to Inorganic Chemical Nomenclature Part 1, Binary Compounds

Intro to Inorganic Chemical Nomenclature Part 1, Binary Compounds. This lesson was divided into two parts Part 1 Binary Compounds In this first video we are studying the nomenclature of Binary Compounds There is also a second video dealing with the nomenclature of Polyatomic Compounds .

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Intro to Inorganic Chemical Nomenclature Part 1, Binary Compounds

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  1. Intro to Inorganic Chemical Nomenclature Part 1, Binary Compounds This lesson was divided into two parts Part 1 Binary Compounds • In this first video we are studying the nomenclature of Binary Compounds • There is also a second video dealing with the nomenclature of Polyatomic Compounds. • Youtube ‘Inorganic Chemical Nomenclature Part 2 Polyatomic Compounds’

  2. Intro to Inorganic Chemical NomenclaturePart 1 Binary Compounds Chemical Nomenclature = writing the formulas and names of chemicals. Using three systems of inorganic nomenclature … the Stock system the Prefix system the Ous-Ic system This requires that you learn the names, formulas and oxidation numbers (Ox #’s) of a variety of monatomic elements and polyatomic ions needed for binary and polyatomic compounds. This lesson is designed for a 1st semester college chemistry student and assumes that the student already has a working knowledge of electron configuration, electronegativity, chemical bonding, and acid ionization.

  3. Intro to Inorganic Chemical Nomenclature H2O1 H2O (H)2O OH2 /  Chemical Formulas of Binary Compounds: Binary compounds are made of two different kinds of atoms. A chemical formula tells us which atoms and how many atoms of each kind are present in a chemical compound. Look at the structure of a water molecule. Each water molecule contains 2 hydrogen atoms and 1 oxygen atom. A subscript of ‘1’ is never written in formulas. Look at the formulas on the right and identify the error in each. / /

  4. Electronegativity (EN) values of A-group Elements • H2O • EN: 2.1 (H) < 3.5 (O) • The less EN atom is listed first. • Practice: • Write the formula of a compound made of … • one S & two Na atoms • Na2S1.0 (Na) < 2.5 (S) • one P & three Br atoms • PBr32.1 (P) < 2.8 (Br) • two Cl’s & one Mg atom • MgCl2 1.2 (Mg) < 3.0 (Cl) In formulas of ionic compounds, symbols of metals precede nonmetals because all metals have lower EN values than any nonmetal.

  5. Chemical Formulas of Binary Compounds Use the table of EN values to write the chemical formulas of the compounds shown below… Ca (1.0) < F (4.0) CaF2 C (2.5) < O (3.5) CO2 EN: Al (1.5) < O (3.5) Al2O3

  6. Some Exceptions in Chemical Formulas of Binary Compounds • The least Electronegative atom in binary compounds are usually listed first, but there are a few historical exceptions … • In the formulas of hydrocarbon compounds (abbreviated HC’s), which are compounds containing only hydrogen and carbon, C (EN=2.5) is listed before H (EN=2.1), even though C has the higher EN value. • Most formulas of binary compounds, in which H is listed first, are acids, such as hydrochloric acid, HCl and hydrofluoric acid, HF. • HC’s are not acidic so their H’s are listed last. CH4, methane, is the major component of natural gas. C2H6, ethane is the 2nd largest component of natural gas

  7. More Exceptions in Chemical Formulas of Binary Compounds • In the formulas of binary compounds containing nitrogen, N is usually listed first regardless of its EN value. • Ammonia, NH3, is not acidic. It’s a moderately strong base. • Listing H first would make ammonia look acidic … H3N In N2O5, N (3.0) < O (3.5) N is less EN and written first. In ammonia, NH3, EN N (3.0) > H (2.1), but N is written first. / /

  8. Naming Binary Compounds There are three systems for naming binary compounds The Stock System (the most comprehensive) e.g., sodium chloride The Prefix System (for nonmetal compounds only) e.g., carbon monoxide, carbon dioxide The ous-ic system (has limited use) e.g., ferrous oxide, ferric oxide

  9. The Stock System for Naming Binary Compounds CaCl2 = calcium chloride Al2O3 = aluminum oxide name of less EN atom first name of more EN atom ends in ‘ide’ name of less EN atom first name of more EN atom ends in ‘ide’ a space between a space between oxygen oxide chlorine chloride • In ionic compounds (made of metal cations, ⊕ and nonmetal anions, ⊖), the less EN atom is a metal cation, and the more EN atom is a nonmetal anion. • The name of the metal cation is the same as the element’s name but the anion’s name ends in ‘ide’. • Note that the Stock system name does not tell us the relative number of atoms in the formula. This will be explained later.

  10. Learn the anion names & charges. selenide(-2) sulfide (-2) Nonmetal anions gain enough electrons to fill their valence shell to become isoelectronic with the nearest noble gas. oxide (-2) hydride (-1) phosphide (-3) nitride (-3) carbide (-4) fluoride (-1) Anions typically have only 1 possible Ox #, which is easy to learn if you know their Group number on the PD table chloride (-1) bromide (-1) iodide (-1)

  11. Practice naming these binary compounds using the Stock system: K3P MgO Al2S3 Ca3N2 MgF2 LiI Be2C potassium phosphide magnesium oxide aluminum sulfide calcium nitride magnesium fluoride lithium iodide beryllium carbide BaBr2 CaH2 Na2Se SrCl2 B2O3 SiC HF barium bromide calcium hydride sodium selenide strontium chloride boron oxide silicon carbide hydrogen fluoride Note that the last three examples are not ionic compounds. They are composed of metalloids and/or nonmetals only, yet the Stock system names all compounds as if they were ionic. The less EN atom is first (using the atom’s name). The more EN atom is last (using the anion’s ‘ide’ name).

  12. Writing Chemical Formulas of Binary Compounds In order to write formulas and name compounds, you will need the ‘oxidation numbers’ (Ox #’s) of the atoms/ions in a compound. Ox #’s are explained in detail in a video entitled ‘Oxidation Numbers’ and will only be discussed briefly in this lesson. What is an oxidation number (Ox #)? Ox # is a charge assigned to an atom or ion in a compound. All pure elements have an Ox # = 0, e.g., Ox # Cu=0, H2=0, S8=0. About 20 elements have only one Ox # (fixed Ox #’s), other than 0, and they must be memorized, but it is easy to do so if you learn their position on the periodic table. The Ox #’s of other atoms/ions are calculated from the chemical formula.

  13. Fixed Ox #’s are highlighted (red and yellow). Metals cannot have ⊖ Ox #’s (they never gain e’s). Most nonmetals can have ⊖ or ⊕ Ox #’s, e.g., Cl in ICl (Cl = -1), Cl in ClF (Cl = +1), Cl in ClO2 (Cl = +4), Cl in ClF7 (Cl = +7). Note that the nonmetal with higher EN always gets a ⊖ Ox # Fixed Ox #’s are easily memorized by knowing their A-Group number on the PD table. Other Ox #’s can all be calculated.

  14. Writing the Formulas of Binary Compounds • Chemical formulas represent the smallest whole number ratio of atoms/ions in a compound. • The positive and negative charges (Ox #’s) must add up to zero; the charges balance. hydrogen: H+ (2.1EN) sulfide: S-2 (2.5EN) calcium: Ca+2 chloride: Cl- boron: B+3 (2.0EN) bromide: Br - (2.8EN) magnesium: Mg+2 phosphide: P-3 1. Obtain ion symbols & Ox #’s (charges) Ca+2 =+2 Cl- -1 -1 = -2 2. Find the total charge needed to balance + & - charges B+3 = +3 Br - -1 -1 -1 = -3 H+1 +1 +1 = +2 S-2 = -2 Mg+2 +2 +2 +2 = +6 P-3 -3 -3 = -6 3. Find the ratio of + and - ions 1 B+3 ion for every 3 Br - ions 2 H+ ions for every 1 S-2 ion 1 Ca+2 ion for every 2 Cl-ions 3 Mg+2 ions for every 2 P-3 ions 4. Use subscripts to write the formulas CaCl2 BBr3 H2S Mg3P2 Nonmetals such as Cl, Br, H, S and P can have ⊕ or ⊖ Ox #’s. An atom is assigned a ⊕ Ox # when it is the less EN atom in a compound and a ⊖ Ox # when it is the more EN atom in a compound.

  15. Practice writing the chemical formulas of binary compounds: A chemical formula shows the lowest whole number ratio of ions such that the total positive and negative charges are equal. The ‘Inverse rule’ is an easy way to find this ratio. Consider zinc phosphide. Zn+2 P-3 Zn3P2 The number of Zn cations (3) equals the charge of the anion (-3), and the number of P anions (2) equals the charge of the cation (+2). But remember to reduce this to the lowest whole number ratio. Consider beryllium carbide. Be+2 C-4 Be4C2  Be2C Mg+2 O-2 MgO K+ N-3 K3N Ba+2 F- BaF2 SiI4 Si+4 I- Be2C Be+2 C-4 Ca+2 H- CaH2 Li2Se Li+ Se-2 Na3P Na+ P-3 Zn3P2 Zn+2 P-3 Al+3 S-2 Al2S3 B2O3 B+3 O-2

  16. Finding an Ox # in Compounds Containing a Multivalent Ion water = H2O water ≠ HO2or H3O or HO, etc. because the Ox # H = +1 and Ox # O = -2 In order to combine elements in a chemical formula in the correct ratio, you need to know the Ox #’s of each element. You will also need to know these Ox #’s for writing chemical names. However many elements are ‘multivalent’; they have more than one possible Ox #. Fortunately, it is always true that at least one of the elements in a binary compound will have an Ox # that is known for certain and so the other element’s Ox # can be calculated. Example 1: Manganese has 5 different Ox #’s in its compounds, i.e., +2, +3, +4, +6 and +7. Calculate the Ox # of Mn in MnCl2. Answer: Mn = +2 Here’s why: The Ox # of Cl is -1 because it is more EN than Mn. Chloride is always -1. The total negative charge in MnCl2 = (Cl-1 × 2) = -2. So the total positive charge of Mn must be +2, and the Ox # of Mn must be +2.

  17. Example 2: Calculate the Ox # of Mn in Mn2O3 Answer: Mn = +3 Here’s why: The Ox # of O is always -2. The total negative charge of three O’s = (-2 × 3) = -6 The total positive charge of both Mnions must be +6 (total ⊕ = total ⊖). So each Mn has a charge of (+6/2) = +3 or solve as a math equation: Let Ox # of Mn = x The sum of all Ox #’s = 0 Mn2O3 = 0 (x)*2 + (-2)*3 = 0 2x – 6 = 0 x = +6/2 = +3  Mn+3 or use the Inverse Rule: Mn2O3 -2 +3

  18. Practice: Calculate the Ox # of the underlined ion in each formula +1 -2 +4 -3 -1 +6 -2 +4 +5 -2 -1 +7 -3 +5 -2 +5 +3 -4 +3 -1

  19. Naming Binary Compounds Containing a Multivalent Ion: Iron (Fe), like manganese (Mn) can exhibit more than one Ox #. There are two kinds of iron chloride, FeCl2 and FeCl3. The name ‘iron chloride’ is thus ambiguous. In binary compounds containing cations with more than one Ox #, the Ox # of the cation is written in Roman numerals (in parentheses) immediately after the cation. Thus FeCl2 is named iron(II) chloride and FeCl3 is named iron(III) chloride. There are two different forms of iron chloride. Iron(II) chloride is green. Iron(III) chloride is yellow/rusty colored. Each different chemical compound must have its own, unique, unambiguous name.

  20. Look at the formulas and names of two kinds of iron oxide, FeO and Fe2O3. Please read carefully: The Ox # listed immediately after the cation indicates the charge on the cation, not necessarily the number of anions in the formula. To name a compound, write the ion symbols and determine their Ox #’s from the combining ratio given in the formula. The anion usually has only one possible Ox #, so calculate the Ox # of the cation remembering that the total ⊕ charge and ⊖ charges in compounds are equal. FeO is black Fe2O3 is rusty/red

  21. Naming Binary Compounds Containing a Multivalent Ion: nitride: N-3 (Group 5A)(N is more EN than Au, so it uses its negative Ox #) oxide: O-2 (Group 6A) O is more EN than Cl, O always has an Ox # of -2 Identify the Ox # that is known for certain (usually the anion’s). Cl+, Cl+3, Cl+5 or Cl+7 If allowed, check the periodic table for the possible charges of the other ion. Au+ or Au+3 Cl2O5 means 2 chlorines for every 5 oxide ions. Determine the ratio of ions in the formula Au3N means 3 gold ions for every 1 nitride ion. Cl+5: +5 +5 = +10 O 2-: -2 -2 -2 -2 -2 = -10 2 Cl+5atoms are needed for every 5 O-2 ions. Au+ +1 +1 +1 = +3 N-3 = -3 3 Au+ ions are needed for every 1 N-3 ion Find what charge must be on the multivalent ion to balance all charges Write the name of the compound gold(I) nitride chlorine(V) oxide

  22. Practice Naming Binary Compounds Containing a Multivalent Ion: Determine Ox #’s of the ions in the compounds below. Use these Ox #’s to write Stock system names of the compounds. Fe+3 O-2 Fe+2O-2 iron(II) oxide iron(III) oxide Mn+4 S-2 Cr+6 O-2 chromium(VI) oxide manganese(IV) sulfide Co+3 Cl- Ni+3 F- cobalt(III) chloride nickel(III) fluoride Co+2 O-2 Cu+2 O-2 copper(II) oxide cobalt(II) oxide Cu+ O-2 Sn+4 N-3 tin(IV) nitride copper(I) oxide Sn+2 N-3 Au+3 Br- tin(II) nitride gold(III) bromide

  23. Practice Writing Formulas of Binary Compounds Containing Multivalent Ions: Cr2O3 CoP Cr+3O-2 Co+3P-3 VCl5 V+5 Cl- NiF2 Ni+2 F- TiO2 WC W+4 C-4 Ti+4 O-2 Note: The formula of a binary compounds does not show the charge of the cation or the anion. Do not write any charges in binary compound formulas. For example, sodium chloride’s formula is NaCl, not Na+Cl-.

  24. Binary Acids: Binary acids contain hydrogen, H, that is covalently bonded to a non metal. Hydrogen chloride, HCl, is an example of a binary acid. When dissolved in water, hydrogen chloride is named hydrochloric acid because it releases an acidic H+ion when it ionizes. Learn the names and formulas of the five common binary acids, listed below. hydrogen fluoride hydrogen chloride hydrogen bromide hydrogen iodide hydrogen sulfide hydrofluoric acid hydrochloric acid hydrobromic acid hydroiodic acid hydrosulfuric acid HF  H+ + F- HCl  H+ + Cl- HBr  H+ + Br- HI  H+ + I- H2S  2H+ + S-2

  25. Summary of Stock System Nomenclature for Binary Compounds • There is > 1 tin oxide, chromium oxide, copper bromide. • Sn, Cr, Cu have > 1 Ox # • Sn (+2, +4), Cr (+2, +3, +6), Cu (+1, +2) • Ox #’s must be included in the name (written in Roman numerals). • There is only one sodium chloride, calcium chloride, aluminum oxide, zinc sulfide, and silver phosphide. • Na, Ca, Al, Zn, Ag have only 1 Ox # each. • Na & Ag (+1), Ca & Zn (+2), Al (+3) • The Ox # is not stated in the name.

  26. The Prefix System for Binary Compounds For binary compounds containing two non-metals, a Greek or Latin prefix is attached to the name of an element to indicate the number of atoms of that element in the compound. Number 1 2 3 4 5 6 Prefix mono di tri tetra penta hexa Formula CO CO2 SO3 CCl4 PCl5 SF6 Prefix System Name carbon monoxide carbon dioxide sulfur trixode carbon tetrachloride phosphorus pentachloride sulfur hexafluoride • 7 = hepta, 8 = octa, 9 = ennea, 10 = deca • Although this system is used almost exclusively for non-metal/non-metal compounds, occasionally, it is used when a metal is present. • Attach a prefix to the 2nd atom in the formula (always). • Attach a prefix to the 1st atom in the formula (only if there is more than one of them).

  27. Name the following compounds using both the Prefix system and the Stock system: Formula N2O NO NO2 N2O3 N2O4 N2O5 ICl CS2 SO2 PCl3 P2O5 SCl6 MnO2 Prefix System Name dinitrogen monoxide nitrogen monoxide nitrogen dioxide dinitrogen trioxide dinitrogentetr(a)oxide dinitrogen pent(a)oxide iodine monochloride carbon disulfide sulfur dioxide phosphorus trichloride diphosphorus pent(a)oxide sulfur hexachloride manganese dioxide Stock System Name nitrogen(I) oxide nitrogen(II) oxide nitrogen(IV) oxide nitrogen(III) oxide nitrogen(IV) oxide nitrogen(V) oxide iodine(I) chloride carbon(IV) sulfide sulfur(IV) oxide phosphorus(III) chloride phosphorus(V) oxide sulfur(VI) chloride manganese(IV) oxide

  28. The “Ous-Ic” System For binary compounds in which the cation usually has only 2 oxidation states, the old “ous-ic” system is sometimes used. In a few cases, when the English name of the metal atom is awkward, the Latin name of the metal is used instead. Then the suffix “ous” is added for the lower oxidation number and “ic” for the higher oxidation number. Symbol Cu Fe Pb Sn Au Hg Pt Co Name copper iron lead tin gold mercury platinum cobalt Ion Charge & Name Cu+ = cuprous, Cu+2 = cupric Fe+2 = ferrous, Fe+3 = ferric Pb+2 = plumbous, Pb+4 = plumbic Sn+2 = stannous, Sn+4 = stannic Au+ = aurous, Au+3 = auric Hg+ = mercurous, Hg+2 = mercuric Pt+2 = platinous, Pt+4 = platinic Co+2 = cobaltous, Co+3 = cobaltic Latin Name cuprum ferrum plumbum stannum aurum --- --- ---

  29. Name the following compounds using the “ous-ic” system. Formula PbCl2 PbCl4 SnBr2 SnBr4 Cu2O CuO FeO Fe2O3 Au2S3 PtF2 PtS2 Hg4C Hg3N2 Ous-Ic Name plumbous chloride plumbic chloride stannous bromide stannic bromide cuprous oxide cupric oxide ferrous oxide ferric oxide auric sulfide platinous fluoride platinic sulfide mercurous carbide mercuric nitride Stock System Name lead(II) chloride lead(IV) chloride tin(II) bromide tin(IV) bromide copper(I) oxide copper(II) oxide iron(II) oxide iron(III) oxide gold(III) sulfide platinum(II) fluoride platinum(IV) sulfide mercury(I) carbide mercury(II) nitride

  30. Peroxides: • A reactive type of compound, called ‘peroxides’, has important commercial and industrial applications. The most familiar example is hydrogen peroxide, H2O2. H2O2 hydrogen peroxide ‘per’ means one more O than the normal oxide. H2O hydrogen oxide • H2O2 is one of the strongest oxidizers known. • 35 – 50% aqueous solutions are used industrially for pulp and paper bleaching. • Up to 12% H2O2 is used as hair bleach and 3% H2O2 is sold as a household disinfectant. • Peroxides are unusual, in that the ‘O’ in a peroxide has an Ox # = -1 and the formula of the peroxide anion is written O2-2(because the peroxide anion is a bonded pair of O’s). • Recall that ‘O’ is in Group 6A, it will be stable when it gains 2 electrons and becomes oxide, O-2, so it is not surprising that peroxide, O2-2, is so reactive (unstable).

  31. Group 1A and 2A metal peroxides have some interesting applications. For example, sodium peroxide, Na2O2, converts carbon dioxide to oxygen and sodium carbonate. Na2O2 + CO2 Na2CO3 + ½ O2 Both lithium peroxide and sodium peroxide have been used to regenerate oxygen from exhaled air in confined spaces, such as submarines and spacecraft. Peroxide Practice: Write the name or formula of the following compounds. Spelling counts. Formula H2O H2O2 BaO2 K2O2 K2O CaO2 Stock System Name hydrogen oxide (Prefix name: dihydrogen monoxide) hydrogen peroxide barium peroxide potassium peroxide potassium oxide calcium peroxide Ox # & Charges H+O-2 H+O2-2 Ba+2O2-2 K+O2-2 K+O-2 Ca+2 O2-2 Note that peroxide formulas, such as H2O2, Na2O2, etc. are not reduced to the lowest whole number ratio. Do not write HO or NaO. All peroxides contain a pair of bonded O’s. Finished Part 1.

  32. Congrats, you just completed inorganic chemical nomenclature part 1 on Binary Compounds There is also a second video dealing with the nomenclature of Polyatomic Compounds. Youtube ‘Inorganic Chemical Nomenclature Part 2 Polyatomic Compounds’

  33. Intro to Inorganic Chemical Nomenclature Part 2, Polyatomic Compounds This lesson was divided into two parts Part 2 Polyatomic Compounds • In this video we will study the nomenclature of Polyatomic Compounds • There is also a first video in which I presented the nomenclature of Binary Compounds. You should complete that video first. • Youtube ‘Inorganic Chemical Nomenclature Part 1 Binary Compounds’

  34. Inorganic Nomenclature Part 2 Polyatomic Compounds Oxy Acids: Oxyacids contain H, O and another nonmetal atom. Many oxyacids are commonly found in cleaning products, fruits, food ingredients, industrial chemicals, etc. • Phosphoric acid, H3PO4, is used to pickle steel and is the flavour in root beers and colas. • Sulfuric acid, H2SO4, is the electrolyte in the automobile lead-acid battery (35% H2SO4). • Carbonic acid, H2CO3, is formed when carbon dioxide, CO2, is dissolved in water (H2O + CO2 H2CO3). Carbonated beverages contain carbonic acid. • A 5% solution of acetic acid, CH3COOH, in water is sold as vinegar.

  35. Here are eight important oxyacids. Some of these exist with varying numbers of oxygen atoms. The ‘main’ oxyacids, the –ic acids, and their names are highlighted. Acetic CH3COOH Carbonic H2CO3 Sulfuric H2SO4 H2SO3 Phosphoric H3PO4 H3PO3 H3PO2 Chloric HClO4 HClO3 HClO2 HClO Iodic HIO4 HIO3 HIO2 HIO ic acids per … ic … ic … ous hypo … ous Nitric HNO3 HNO2 Bromic HBrO4 HBrO3 HBrO2 HBrO When oxyacids react, they release hydrogen ions, H+, and leave behind polyatomic anions. HNO3 H+ + NO3-andH2SO4 2H+ + SO4-2 and H3PO4 3H+ + PO4-3 Acetate CH3COO- Carbonate CO3-2 Sulfate SO4-2 SO3-2 Phosphate PO4-3 * HPO3-2 ** H2PO2- Chlorate ClO4- ClO3- ClO2- ClO- Iodate IO4- IO3- IO2- IO- ate anions per … ate … ate … ite hypo … ite Nitrate NO3- NO2- Bromate BrO4- BrO3- BrO2- BrO- ** H3PO2 only has 1 acidic H, so hypophosphite is H2PO2- * H3PO3 only has 2 acidic H’s, so phosphite is HPO3-2

  36. +1 +1 +1 +1 +1 +1 -1 -2 -3 -2 -1 -1 Practice: Study the structures and learn the formulas and names of the acids and their anions. + + 2 CH3COOH acetic acid CH3COO- acetate H2SO4 sulfuric acid SO4-2 sulfate + + 3 2 H3PO4 phosphoric acid PO4-3 phosphate H2CO3 carbonic acid CO3-2 carbonate + + NO3- nitrate ClO3- chlorate HNO3 nitric acid HClO3 chloric acid

  37. Practice: Study the Lewis structures and learn the formulas & names of the acids and their anions. CH3COOH acetic acid CH3COO- acetate H2SO4 sulfuric acid SO4-2 sulfate H3PO4 phosphoric acid PO4-3 phosphate H2CO3 carbonic acid CO3-2 carbonate NO3- nitrate ClO3- chlorate HNO3 nitric acid HClO3 chloric acid

  38. +1 +1 +1 +1 -1 -1 Other Polyatomic Ions: A few other important polyatomic ions are shown below. HCN, hydrogen cyanide is acidic. In water it is called hydrocyanic acid. Although it is a weak acid and has a sweet almond odour, it is highly toxic when ingested. HCN  H+ + CN- The formula of water, H2O, looks like other binary acids, but water is completely neutral. When a H+ ion is removed from water, hydroxide ion, OH-, a strong base is formed. Ammonia, NH3, is a moderately strong base with a pungent odour – the smell of Windex. When NH3 reacts with H+, an ammonium cation, NH4+, is formed: NH3 + H+ NH4+ NH4+ (ammonium ion) is the only polyatomic ion listed that is a cation. Its ‘ium’ ending indicates that it is a cation. The polyatomic anions have endings ‘ate’, ‘ite’, and ‘ide’. + HCN hydrocyanic acid CN- cyanide + H2O water OH- hydroxide + NH4+ ammonium NH3 ammonia

  39. Other Polyatomic Ions: A few other important polyatomic ions are shown below. HCN, hydrogen cyanide is acidic. In water it is called hydrocyanic acid. Although it is a weak acid and has a sweet almond odour, it is highly toxic when ingested. HCN  H+ + CN- The formula of water, H2O, looks like other binary acids, but water is completely neutral. When a H+ ion is removed from water, hydroxide ion, OH-, a strong base is formed. Ammonia, NH3, is a moderately strong base with a pungent odour – the smell of Windex. When NH3 reacts with H+, an ammonium cation, NH4+, is formed: NH3+ H+ NH4+ NH4+ (ammonium ion) is the only polyatomic ion listed that is a cation. Its ‘ium’ ending indicates that it is a cation. The polyatomic anions have endings ‘ate’, ‘ite’, and ‘ide’. HCN hydrocyanic acid CN- cyanide H2O water OH- hydroxide NH4+ ammonium NH3 ammonia

  40. Monoprotic and Polyprotic Acids: Acids like CH3COOH, HNO3, HNO2, HClO4, HClO3, HClO2, HClO, etc. have only one ionizableH+ ion per molecule; these are called monoproticacids. The three H’s bonded to C in CH3COOH are not ionizable. Acids like H2CO3, H2SO4, H2SO3 and H3PO4 can release more than one H+ ion per molecule; they are called polyproticacids because they can release more than one H+ (proton). When polyprotic acids lose some but not all of their ionizable H’s, important polyatomic anions form. H2CO3 H+ + HCO3-  H+ + H2SO4  H+ + HSO4- H+ + H2SO3  H+ + HSO3- H+ + H3PO4 H+ + H2PO4- H+ + HPO4-2 H+ + HCO3- CO3-2 HSO4- SO4-2 HSO3- SO3-2 H2PO4- HPO4-2 PO4-3 bicarbonate or monohydrogen carbonate carbonate bisulfate or monohydrogen sulfate sulfate bisulfite or monohydrogen sulfite sulfite dihydrogen phosphate monohydrogen phosphate phosphate

  41. The stepwise ionization of some polyprotic acids is shown. H3PO4 phosphoric acid H2SO4 sulfuric acid H2PO4- dihydrogen phosphate HSO4- bisulfate HSO4- bisulfate SO4-2 sulfate H2PO4- dihydrogen phosphate HPO4-2 monohydrogen phosphate PO4-3 phosphate HSO3- bisulfite HPO4-2 monohydrogen phosphate H2SO3 sulfurous acid

  42. Formulas and Names Involving Polyatomic Ions: Compounds containing polyatomic ions are named the same as binary compounds. Formulas containing polyatomic ions are written the same as binary compounds, with one difference … sodium chloride is NaCl calcium chloride is CaCl2 Parentheses are not placed around monatomic ions like Cl-, even when several are present in the formula. sodium hydroxide is NaOH calcium hydroxide is Ca(OH)2 Parentheses are placed around polyatomic ions like OH-, only when several are present in the formula. Ammonium hydroxide, NH4OH, contains two polyatomic ions, the ammonium cation, NH4+, and the hydroxide anion, OH- In ammonium cyanide, NH4CN, the N atom occurs twice. They remain separate so that the both the ammonium cation, NH4+, and the cyanide anion, CN-, are recognized.

  43. Practice: Write names or formulas in the empty cells. Use the Stock System. Name zinc acetate iron(III) acetate chromium(VI) nitrite manganese(VII) nitrate aluminum sulfate aluminum bisulfate potassium sulfite iron(II) bisulfite nickel(II) perchlorate tin(II) chlorate lead(IV) chlorite mercury(I) hypobromite cobalt(III) bromate chromium(III) perbromate ions & Ox #’s Zn+2 CH3COO- Fe+3 CH3COO- Cr+6 NO2- Mn+7NO3- Al+3 SO4-2 Al+3 HSO4- K+ SO3-2 Fe+2 HSO3- Ni+2 ClO4- Sn+2 ClO3- Pb+4 ClO2- Hg+BrO- Co+3 BrO3- Cr+3BrO4- Zn(C2H3O2)2 Fe(C2H3O2)3 Cr(NO2)6 Mn(NO3)7 Al2(SO4)3 Al(HSO4)3 K2SO3 Fe(HSO3)2 Ni(ClO4)2 Sn(ClO3)2 Pb(ClO2)4 HgBrO Co(BrO3)3 Cr(BrO4)3

  44. Practice: Write names or formulas in the empty cells. Use the Stock System. Name strontium iodite ammonium sulfate lithium hypoiodite beryllium iodate copper(II) bromite aluminum carbonate copper(II) bicarbonate barium phosphate cadmium periodate tungsten(VI) cyanide molybdenum(VI) carbonate vanadium(V) sulfite platinum(IV) phosphate mercury(II) bisulfate ions & Ox #’s Sr+2 IO2- NH4+ SO4-2 Li+ IO- Be+2 IO3- Cu+2 BrO2- Al+3CO3-2 Cu+2 HCO3- Ba+2 PO4-3 Cd+2 IO4- W+6 CN- Mo+6 CO3-2 V+5 SO3-2 Pt+4 PO4-3 Hg+2 HSO4- Formula Sr(IO2)2 (NH4)2SO4 LiIO Be(IO3)2 Cu(BrO2)2 Al2(CO3)3 Cu(HCO3)2 Ba3(PO4)2 Cd(IO4)2 W(CN)6 Mo(CO3)3 V2(SO3)5 Pt3(PO4)4 Hg(HSO4)2

  45. In most oxyacids, adding or subtracting O’s to a formula does not change the number of ionizable H’s. HNO3 and HNO2 are both monoprotic acids. H2SO4and H2SO3 are both diprotic acids. HClO4, HClO3, HClO2 and HClO are all monoprotic acids. The oxyacids of P are unique. H3PO4 is triprotic, but H3PO3 is only diprotic, and H3PO2 is monoprotic. Examine the structures of these oxyacids and note that acidic H’s are bonded to O, not to P.

  46. HPO4-2, monohydrogen phosphate H2PO4-, dihydrogen phosphate PO4-3, phosphate H3PO4, phosphoric acid Because phosphorous acid (H3PO3) has only two ionizable H’s, HPO3-2 is fully ionized and can be named monohydrogen phosphite or simply ‘phosphite’. HPO3-2, monohydrogen phosphite or simply ‘phosphite’ H2PO3-, dihydrogen phosphite H3PO3, phosphorous acid Because hypophosphorous acid (H3PO2) has only one ionizable H, H2PO2- is fully ionized and can be named dihydrogen hypophosphite or simply ‘hypophosphite’. H2PO2-, dihydrogen hypophosphite or simply ‘hypophosphite’ H3PO2, hypophosphorous acid

  47. As we are seeing, there are several conventions for naming the anions of partly ionized polyprotic acids. The student has latitude here, however, any correct name must identify the compound unambiguously. Try naming the following compounds using more than one correct name. Formula H3PO4 NaH2PO4 K2HPO4 LiH2PO3 Ag2HPO3 NaH2PO2 (NH4)2HPO4 (NH4)2HPO3 NH4H2PO4 (NH4)2KPO4 Name phosphoric acid or hydrogen phosphate sodium dihydrogen phosphate or monosodium phosphate potassium monohydrogen phosphate or dipotassium phosphate lithium dihydrogen phosphite or monolithium phosphite silver monohydrogen phosphite or silver phosphite sodium dihydrogen hypophosphite or sodium hyposphosphite diammonium monohydrogen phosphate or diammonium phosphate diammonium monohydrogen phosphite or ammonium phosphite ammonium dihydrogen phosphate or monoammonium phosphate diammonium potassium phosphate ions & Ox #’s H+ PO4-3 Na+ H2PO4- K+ HPO4-2 Li+ H2PO3- Ag+ HPO3-2 Na+ H2PO2- NH4+ HPO4-2 NH4+ HPO3-2 NH4+ H2PO4- NH4+ K+ PO4-3 The number of H’s need not be stated, provided the number of other cations is explicitly stated in the name. Prefixes like ‘di’ or ‘tri’ should only be used when partially ionized polyprotic acids are being named.

  48. For compounds of monovalent cations (Li+, Na+, K+, NH4+, etc.) we have seen that there are several acceptable names … e.g., K2HPO4 = dipotassiummonohydrogen phosphate or potassium monohydrogen phosphate ordipotassiumphosphate However, when polyvalent cations, like Ca+2, Al+3, etc. are combined with partially ionized acids, the convention is to state the number of H’s but not the number of polyvalent metal cations, as follows … Ca(H2PO4)2 CaHPO4 Al(H2PO4)3 Al2(HPO4)3 Fe2(HPO4)3 SnHPO4 Pb(H2PO3)4 Pd(H2PO2)4 Pd(H2PO2)2 calcium dihydrogen phosphate calcium monohydrogen phosphate aluminum dihydrogen phosphate aluminum monohydrogen phosphate iron(III) monohydrogen phosphate tin(II) monohydrogen phosphate lead(IV) dihydrogen phosphite palladium(IV) dihydrogen hypophosphite or palladium(IV) hypophosphite palladium(II) dihydrogen hypophosphite or palladium(II) hypophosphite Ca+2 H2PO4- Ca+2 HPO4-2 Al+3 H2PO4- Al+3 HPO4-2 Fe+3 HPO4-2 Sn+2 HPO4-2 Pb+4 H2PO3- Pd+4 H2PO2- Pd+2 H2PO2-

  49. Practice: Write the name or formula of the following compounds. Spelling counts.The column on the right will not be marked. Formula Mg(CH3COO)2 (NH4)2SO4 Fe2(CO3)3 Ba(NO3)2 Mn(ClO2)7 Cd(IO4)2 AlH3 Be3N2 Hg(BrO)2 H­2SO3 HClO3 (NH4)2HPO4 Zn(H2PO2)2 Stock System Name magnesium acetate ammonium sulfate iron(III) carbonate barium nitrate manganese(VII) chlorite cadmium periodate aluminum hydride beryllium nitride mercury(II) hypobromite sulfurous acid chloric acid ammonium monohydrogen phosphate or diammonium phosphate zinc dihydrogen hypophosphite or zinc hypophosphite Ox # & Charges Mg+2CH3COO- NH4+ SO4-2 Fe+3CO3-2 Ba+2NO3- Mn+7ClO2- Cd+2IO4- Al+3 H- Be+2 N-3 Hg+2 BrO- H+ SO3-2 H+ ClO3- NH4+HPO4-2 Zn+2 H2PO2-

  50. Other Common Acids: A few other inorganic acids are commonly encountered in the laboratory. Study the structures and names of these acids and their anions. Permanganic acid, HMnO4, is monoprotic. Its potassium salt, potassium permanganate (KMnO4) is a dark purple-colored reagent that is often used in the lab as a strong oxidizing titrant. Mn is in its highest oxidation state, +7, (which contributes to its strength as an oxidizer). permanganic acid, HMnO4 permanganate, MnO4- Chromic acid, H2CrO4, is a diprotic acid and strong oxidizer. Its potassium salt, potassium chromate, K2CrO4, is used as an indicator for measurement of chloride by silver nitrate titration. Cr is in its highest oxidation state, +6, (which contributes to its strength as an oxidizer). chromic acid, H2CrO4 chromate, CrO4-2 Dichromic acid, H2Cr2O7 is another strongly oxidizing diprotic acid. Its potassium salt, potassium dichromate ( K2Cr2O7) is a common lab reagent. Can you calculate the Ox # of Cr in it? dichromic acid, H2Cr2O7 dichromate, Cr2O7-2

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