1 / 55

Nomenclature of Compounds

Nomenclature of Compounds. Example 5.1 Constant Composition of Compounds. Two samples of carbon dioxide, obtained from different sources, are decomposed into their constituent elements. One sample produces 4.8 g of oxygen and 1.8 g of carbon, and the other sample produces 17.1 g of oxygen and

chandler-lambert
Télécharger la présentation

Nomenclature of Compounds

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Nomenclature of Compounds

  2. Example 5.1Constant Composition of Compounds Two samples of carbon dioxide, obtained from different sources, are decomposed into their constituent elements. One sample produces 4.8 g of oxygen and 1.8 g of carbon, and the other sample produces 17.1 g of oxygen and 6.4 g of carbon. Show that these results are consistent with the law of constant composition. SOLUTION Compute the mass ratio of one element to the other by dividing the larger mass by the smaller one. For the first sample: For the second sample: Since the ratios are the same for the two samples, these results are consistent with the law of constant composition. SKILLBUILDER 5.1 Constant Composition of Compounds Two samples of carbon monoxide, obtained from different sources, are decomposed into their constituent elements. One sample produces 4.3 g of oxygen and 3.2 g of carbon, and the other sample produces 7.5 g of oxygen and 5.6 g of carbon. Are these results consistent with the law of constant composition? Answer: Yes, because in both cases For More Practice Example 5.16; Problems 25, 26.

  3. Example 5.2 Writing Chemical Formulas Write a chemical formula for each compound. (a) the compound containing two aluminum atoms to every three oxygen atoms (b) the compound containing three oxygen atoms to every sulfur atom (c) the compound containing four chlorine atoms to every carbon atom SOLUTION (a) Al2O3 (b) SO3 (c) CCl4 Since aluminum is the metal, it is listed first. Since sulfur is below oxygen on the periodic table and since it occurs before oxygen in Table 5.1, it is listed first. Since carbon is to the left of chlorine on the periodic table and since it occurs before chlorine in Table 5.1, it is listed first.

  4. Example 5.4 Classifying Substances as Atomic Elements, MolecularElements, Molecular Compounds, or Ionic Compounds Classify each substance as an atomic element, molecular element, molecular compound, or ionic compound. (a) krypton (b) CoCl2 (c) nitrogen (d) SO2 (e) KNO3 SOLUTION (a) Krypton is an element that is not listed as diatomic in Table 5.2; therefore, it is an atomic element. (b) CoCl2 is a compound composed of a metal (left side of periodic table) and nonmetal (right side of the periodic table); therefore, it is an ionic compound. (c) Nitrogen is an element that is listed as diatomic in Table 5.2; therefore, it is a molecular element. (d) SO2 is a compound composed of two nonmetals; therefore, it is a molecular compound. (e) KNO3 is a compound composed of a metal and two nonmetals; therefore, it is an ionic compound.

  5. Example 5.4 Classifying Substances as Atomic Elements, MolecularElements, Molecular Compounds, or Ionic Compounds Continued SKILLBUILDER 5.4 Classifying Substances as Atomic Elements, Molecular Elements, Molecular Compounds, or Ionic Compounds Classify each substance as an atomic element, molecular element, molecular compound, or ionic compound. (a) chlorine (b) NO (c) Au (d) Na2O (e) CrCl3 Answers: (a) molecular element (b) molecular compound (c) atomic element (d) ionic compound (e) ionic compound For More Practice Example 5.19, Example 5.20; Problems 43, 44, 45, 46.

  6. Ionic Compounds • Formed due to the attraction between positive and negative charges on ions. • Will always be between a metal and a nonmetal (cation and anion) • The net charge on the ionic compound should be zero. • Formulas tell us the number of each kind of ion contained in the ionic compound

  7. Problem • Which of the following pairs of elements are likely to form an ionic compound? • A) lithium and chloride • B) potassium and oxygen • C) oxygen and chlorine • D) sodium and neon

  8. Formulas and Subscripts • NET CHARGE OF ZERO = POSITIVE CHARGES EQUAL NEGATIVE CHARGES. • SUBSCRIPTS IN FORMULAS TELL US THE NUMBER OF IONS OF A CERTAIN TYPE IN THE COMPOUND. • EXAMPLE: MgCl2 -- 1 Mg2+ ion and 2 Cl- ions

  9. Example 5.3 Total Number of Each Type of Atom in a Chemical Formula Determine the number of each type of atom in Mg3(PO4)2. SOLUTION Mg: There are three Mg atoms (present as Mg2+ ions), as indicated by the subscript 3. P: There are two P atoms. We determine this by multiplying the subscript outside the parentheses (2) by the subscript for P inside the parentheses, which is 1 (implied). O: There are eight O atoms. We determine this by multiplying the subscript outside the parentheses (2) by the subscript for O inside the parentheses (4). SKILLBUILDER 5.3 Total Number of Each Type of Atom in a Chemical Formula Determine the number of each type of atom in K2SO4. Answer: two K atoms, one S atom, four O atoms SKILLBUILDER PLUS Determine the number of each type of atom in Al2(SO4)3. Answer: two Al atoms, three S atoms, twelve O atoms For More Practice Example 5.18; Problems 35, 36, 37, 38.

  10. Example 5.2 Writing Chemical Formulas Continued SKILLBUILDER 5.2 Writing Chemical Formulas Write a chemical formula for each compound. (a) the compound containing two silver atoms to every sulfur atom (b) the compound containing two nitrogen atoms to every oxygen atom (c) the compound containing two oxygen atoms to every titanium atom Answers: (a) Ag2S (b) N2O (c) TiO2 For More Practice Example 5.17; Problems 31, 32, 33, 34.

  11. Writing Ionic Formulas • Example. Write the ionic formula for the ionic compound containing K+ and N3-. • Criss Cross Method

  12. Example 5.5Writing Formulas for Ionic Compounds Write a formula for the ionic compound that forms from aluminum and oxygen. SOLUTION Al3+ O2 1. Write the symbol for the metal and its charge followed by the symbol of the nonmetal and its charge. For many elements, you can determine these charges from their group number in the periodic table (refer to Figure 4.14). 2. Make the magnitude of the charge on each ion (without the sign) become the subscript for the other ion. FIGURE 4.14 Elements that form predictable ions.

  13. Example 5.5 Writing Formulas for Ionic Compounds Continued In this case, the numbers cannot be reduced any further; the correct formula is Al2O3. Cations: 2(3+) = 6+ Anions: 3(2) = 6 The charges cancel. 3. If possible, reduce the subscripts to give a ratio with the smallest whole numbers. 4. Check to make sure that the sum of the charges of the cations exactly cancels the sum of the charges of the anions. SKILLBUILDER 5.5 Write a formula for the compound formed from strontium and chlorine. Answer: SrCl2

  14. Example 5.7 Writing Formulas for Ionic Compounds Write a formula for the compound composed of potassium and oxygen. SOLUTION First write the symbol for each ion along with its appropriate charge from its group number in the periodic table. K+ O2 Then make the magnitude of each ion’s charge become the subscript for the other ion. K+ O2 becomes K2O No reduction of subscripts is necessary in this case. Finally, check to see that the sum of the charges of the cations [2(1+) = 2+] exactly cancels the sum of the charges of the anion (2). The correct formula is K2O. SKILLBUILDER 5.7 Writing Formulas for Ionic Compounds Write a formula for the compound that forms from calcium and bromine. Answer: CaBr2 For More Practice Problems 57, 58.

  15. Example 5.8 Naming Ionic Compounds Containing a Metal That Forms Only One Type of Cation Name the compound MgF2. SOLUTION The cation is magnesium. The anion is fluorine, which becomes fluoride. Its correct name is magnesium fluoride. SKILLBUILDER 5.8 Naming Ionic Compounds Containing a Metal That Forms Only One Type of Ion Name the compound KBr. Answer: potassium bromide SKILLBUILDER PLUS Name the compound Zn3 N2. Answer: zinc nitride For More Practice Example 5.22; Problems 59, 60.

  16. Octet Rule and the formation of ions • All atoms of elements want to attain a full valence electron shell (outermost). • For some elements it is easier to gain electrons (nonmetals) and for others (metals) it is easier to lose electrons. • For the representative elements, the electron configuration after the formation of an ion will be that of a noble gas.

  17. Problem • Write the correct ionic formula for compounds formed between the following ions: • A) Na+ and O2- • B) Al3+ and Br- • C) Mg2+ and Cl- • D) Al3+ and S2-

  18. Ions

  19. Problem • Write the correct formula for the ionic compounds formed by the following metals and nonmetals. • A) sodium and sulfur • B) potassium and nitrogen • C) aluminum and iodide • D) lithium and oxygen

  20. Common and Systematic Names • Chemical nomenclature is the system of names that chemists use to identify compounds. • Common names are not based on the chemical composition of compounds. • Systematic names precisely identify the chemical composition of a chemical compound.

  21. Nomenclature Naming of Binary Ionic Compounds • Step 1 – Identify the cation and anion • Step 2 – Name the cation by its element name • Step 3 – name the anion by using its root name and ending in “ide” • Step 4 – Write the name of the cation first and the anion second.

  22. Example 5.9 Naming Ionic Compounds Containing a Metal That Forms More Than One Type of Cation Name the compound PbCl4. SOLUTION The name for PbCl4 consists of the name of the cation, lead, followed by the charge of the cation in parentheses (IV), followed by the base name of the anion, chlor-, with the ending -ide. The full name is lead(IV) chloride. We know the charge on Pb is 4+ because the charge on Cl is 1. Since there are 4 Cl–anions, the Pb cation must be Pb4+. PbCl4 lead(IV) chloride SKILLBUILDER 5.9 Naming Ionic Compounds Containing a Metal That Forms More Than One Type of Cation Name the compound PbO. Answer: lead(II) oxide For More Practice Example 5.23; Problems 61, 62.

  23. Example 5.10 Naming Ionic Compounds Containing a Polyatomic Ion Name the compound K2CrO4. SOLUTION The name for K2CrO4 consists of the name of the cation, potassium, followed by the name of the polyatomic ion, chromate. K2CrO4 potassium chromate SKILLBUILDER 5.10 Naming Ionic Compounds Containing a Polyatomic Ion Name the compound Mn(NO3)2. Answer: manganese(II) nitrate For More Practice Example 5.24; Problems 65, 66.

  24. Problems • NaF • Al2O3

  25. CaCl2 • Mg3N2

  26. Writing formulas from the name • Step 1 – identify the cation and anion • Step 2 – Balance the charges • Step 3 – Write the formula, cation first, using subscripts. • Example – sodium nitride

  27. Write the formulas for these compounds • (a) strontium chloride • (b) potassium iodide • (c) calcium sulfide

  28. Naming ionic compounds that contain transition metals • Two systems – Classical and Stock systems • The Stock system is considered the official system. • In the Stock system a Roman numeral is used to denote the charge on the cation (metal). • The Roman numeral is placed in parentheses immediately after the name of the metal.

  29. In the older system an “ous” ending is given to the cation with the smaller positive charge and an “ic” ending is given the cation with the larger positive charge.

  30. Naming binary ionic compounds with metals that form more than one charge. • Step 1 – Identify the cation and anion • Step 2- determine the charge of the cation from the anion • Step 3 – Name the cation by its element name followed by the charge in Roman numeral form in parentheses • Step 4 – Name the anion as before, using the root name and ending in “ide” • Step 5 – Write the name of the cation first and the name of the anion second.

  31. Example – SnCl2 • Step 1 – the cation is tin (Sn) and the anion is chlorine (Cl) • Step 2 – Use criss cross again to determine charge on tin – Sn2+ or see that you have 2 Cl- = 2- • Step 3 – tin(II) • Step 4 – chlorine  chlor plus ide • Step 5 – tin(II) chloride

  32. Cu2S • FeO • Fe2S3

  33. Problems • Write the name for each of the following compounds using the Stock System. • (a) PbI2 • (b) SnF4 • (c) Fe2O3 • (d) CuO

  34. Indicate the charge on the metal ion. • FeCl2 • Cu2O • PbI4 • Fe2S3

  35. Write formulas for the following compounds. • (a) tin(IV) chloride • (b) chromium(III) sulfide • (c) copper(I) oxide • (d) tin(II) flouride

  36. Iron(II) chloride

  37. Transition and Group 4A metals • Those to remember for our purposes – • Chromium – Cr2+ chromium(II) • Cr3+ chromium(III) • Copper - Cu1+ copper(I) • Cu2+ copper(II) • Iron - Fe2+ iron(II) • Fe3+ iron(III)

  38. Lead Pb2+ Lead(II) • Pb4+ Lead(IV) • Tin Sn2+ Tin(II) • Sn4+ Tin(IV)

  39. Polyatomic ions • A group of atoms that carry a charge. They work as a unit • Only polyatomic with a positive charge is the ammonium ion (NH4+) • Most consist of a nonmetal bonded to oxygen, usually P, S, C, N

  40. Naming polyatomic ions • Most common ending is “ate”. • “ite” ending reserved for those with 1 less oxygen. • Must memorize. • “per----ate” – one oxygen more than “ate” ending. • “hypo---ite” – one oxygen less than “ite” ending

  41. Nitrate • Nitrite • Sulfate • Sulfite • Perchlorate • Chlorate • Chlorite • Hypochlorite

  42. Naming compounds with polyatomic ions • Same rules apply – charges must be balanced; cation named before polyatomic ion name unless ammonium • Na2SO4 – sodium sulfate • BaSO4 –barium sulfate • AgNO3 – silver nitrate • CaCO3 – calcium carbonate

  43. Writing formulas for compounds containing polyatomic ions • Barium hydroxide • Aluminum chlorate • Magnesium bicarbonate • Ammonium oxide

  44. Name the following • Na2CO3 • FeSO3 • CaCl2 • CuF

  45. Name the following compounds • NaNO3 • Ca3(PO4)2 • KOH • NaClO3

  46. Write formulas for the following compounds. • Calcium hydrogen sulfite • Lithium hydrogen carbonate • Ammonium hydroxide • Potassium phosphate

  47. Nomenclature – Binary Ionic Compounds Ionic Compounds Cation: Metal or NH4+ Anion: Nonmetal One charge Multiple charges Single ion Polyatomic ion Alkali metals Alkaline earth metals Ag+, Al3+, All other metals Use root name and end in “ide” Use the name of the polyatomic ion Use the name of the element and a Roman numeral in ( ) for the positive charge on the ion. Use the name of the element or ammonium if NH4+

  48. Binary molecular compounds – two elements, two nonmetals • These compounds have covalent bonds not ionic. • They are held together by a sharing of electrons. • Greek prefixes are used to state the number of each element in the molecule. • The element that occurs first in the formula is written and named first • The second element gets an “ide” ending with the root

More Related