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Modern Chemistry Chapter 7 Chemical Formulas and Chemical Compounds

Modern Chemistry Chapter 7 Chemical Formulas and Chemical Compounds. Section 1. Chemical Names and Formulas. Eight carbon atoms in the molecule. Eighteen hydrogen atoms in the molecule. Chemical Formula. C. H. Molecular compounds – for one molecule

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Modern Chemistry Chapter 7 Chemical Formulas and Chemical Compounds

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  1. Modern ChemistryChapter 7Chemical Formulas and Chemical Compounds

  2. Section 1 Chemical Namesand Formulas

  3. Eight carbon atoms in the molecule Eighteen hydrogen atoms in the molecule Chemical Formula C H Molecular compounds – for one molecule Ionic compounds – for one formula unit; the simplest ratio of cations to anions 8 18

  4. 2 Al atoms 4 SO4 ions 4 O atoms Chemical Formula Al (SO ) 5 ions – two Al 3+ ions and three (SO4) 2- ions 2 4 3

  5. Definitions • Binary Compound – compound with only two types of atoms • Nomenclature – a naming system • Salt- an ionic compound composed of a cation and an anion from an acid

  6. Definitions • Monatomic ions – ions formed from a single atom • For negative monatomic ions, -ide is added to the root name

  7. How can I tell if the compound is ionic or covalent ???? Ionic compounds contain a metal and a nonmetal or a polyatomic ion !!!

  8. Writing Fomulas and Naming Ionic Compounds

  9. Charges on Monatomic Ions 1+ 2+ 3+ 3- 2- 1-

  10. Charges on Transition Metals Ag 1+ Zn 2+ Cu 1+ or 2+ Fe/Cr 2+ or 3+ Sn 2+ or 4+ Pb 2+ or 4+ See list.

  11. Charges of Metals PbO2 and PbO

  12. Polyatomic Ions Page 226

  13. Ionic Compounds Formulas • Write the symbols • Determine the charges • Monatomic ions from the periodic table • Transition metals from a roman numeral • Polyatomic ions from sheet. • Cross the charges. • Reduce to lowest ratio.

  14. Ionic Compounds Names • Write the cation name. • Write the anion name. • Add –ide to the anion if monatomic • Add the roman numeral for any transition metal. • NO PREFIXES!!!!

  15. Ionic Binary Compounds Aluminum Oxide FORMULAS 3+ 2- (charge x subscript)+(charge x subscript)= 0 Al O 3 2 (3+ x ) + (2- x ) = 0 2 3 Al2O3

  16. Ionic Binary Compounds Aluminum Oxide FORMULAS 3+ 2- Al O 3 2 REDUCE IF NECESSARY!! Al2O3

  17. Ionic BinaryCompounds NAMING Mg3N2 NO PREFIXES!! Nitrogen ide Magnesium

  18. Practice Page 223 1. Write formulas for the binary ionic compounds formed between the following elements: a. potassium and iodine b. magnesium and chlorine c. sodium and sulfur d. aluminum and sulfur e. aluminum and nitrogen 2. Name the binary ionic compounds indicated by the following formulas: a. AgCl e. BaO b. ZnO f. CaCl2 c. CaBr2 d. SrF2

  19. Ionic Compounds with Transition Metals FORMULAS Iron (III) Chloride 3+ 1- Fe Cl 1 3 (3+ x ) + (1- x ) = 0 1 3 FeCl3

  20. Ionic Compounds with Transition Metals FORMULAS Tin (II) Oxide 2+ 2- Sn O 1 1 (2+ x ) + (2- x ) = 0 1 1 SnO

  21. Ionic Compounds with Transition Metals FORMULAS Tin (II) Oxide 2+ 2- Sn O 1 2 1 2 REDUCE! SnO

  22. Practice Page 225 1. Write the formula and give the name for the compounds formed between the following ions: a. Cu 2+ and Br −d. Hg 2+ and S 2− b. Fe 2+ and O 2− e. Sn 2+ and F − c. Pb 2+ and Cl −f. Fe 3+ and O 2− 2. Give the names for the following compounds: a. CuO c. SnI4 b. CoF3d. FeS

  23. Ionic Compounds with Transition Metals NAMING PbO ( x 1 ) + ( 2- x 1 ) = 0 2+ NO PREFIXES!! Lead II Oxygen ide

  24. Ionic Compounds with Polyatomic Ions FORMULAS Ammonium Sulfate + 2- (NH ) (SO ) 4 2 4 1 (1+ x ) + (2- x ) = 0 2 1 (NH4)2SO4 Parenthesis are needed if the p. ion has a subscript from the crossed charge – outside the ( ).

  25. Ionic Compounds with Polyatomic Ions NAMING Ca(NO3)2 NO PREFIXES!! Nitrate Calcium

  26. Practice Page 227 1. Write formulas for the following ionic compounds: a. sodium iodide e. copper(II) sulfate b. calcium chloride f. sodium carbonate c. potassium sulfide g. calcium nitrite d. lithium nitrate h. potassium perchlorate 2. Give the names for the following compounds: a. Ag2O b. Ca(OH)2 c. KClO3 d.NH4OH e. Fe2(CrO4)3 f. KClO

  27. Writing Fomulas and Naming Molecular Compounds

  28. Prefixes for Covalent p. 228

  29. Molecular Compound Formulas • Write the symbols. • Use prefixes for subscripts. • DON’T reduce.

  30. Molecular Compound Names • Write the name of the elements. • Order: Smaller group number first; • Same group? Greater period number first. • Add –ide to the second element. • Add prefixes to each element for the number of atoms.

  31. Binary Molecular Compounds FORMULAS Disulfur difluoride S F 2 2 DON'T REDUCE! S2F2

  32. Binary Molecular Compounds NAMING O N 2 4 di nitrogen tetra oxygen ide

  33. Practice Page 229 1. Name the following binary molecular compounds: a. SO3 b. ICl3 c. PBr5 2. Write formulas for the following compounds: a. carbon tetraiodide b. phosphorus trichloride c. dinitrogen trioxide

  34. Acids and Salts • Acids – Chapter 14 • Binary Acids – two elements; hydrogen and one other element • Oxyacids – contain hydrogen, one other element and oxygen • Acid – typically thought of as an H donor; usually referred to as a solution of the compound in water.

  35. Acids and Salts • Salt – an ionic compound • Made from • the cation of a base and • the anion of an acid • Some retain an H in the anion • Example: CO3 2- carbonate HCO3 1- hydrogen carbonate or bicarbonate

  36. p. 230 Salt Definition Animation

  37. p. 230 List of Acids Know these acids: HF, HCl, H3PO4, HNO3, H2SO4 CH3COOH

  38. Section 3 Oxidation Numbers

  39. Oxidation Numbers • Oxidation numbers are numbers assigned to the atoms in a molecular compound or ion that indicates the general distribution of electrons among bonded atoms. • Oxidation numbers are not actual charges. • Oxidation numbers can be useful in naming compounds and writing formulas. -1 +1 +2 +3 -2

  40. Rules for Assigning Oxidation Numbers • Atoms in a pure element have an oxidation number of zero – O2 Ox. # = 0 • Fluorine always has ox. # of -1 • Oxygen almost always has ox. # of -2 except in peroxides such as H2O2 – then it is a -1.

  41. Rules for Assigning Oxidation Numbers • (Rules continued): • Hydrogen’s ox. # is +1 unless it is with metals – then it is -1 • The sum of the ox. # in molecules must be zero, but in polyatomic ions, it is equal to the ions charge.

  42. Oxidation Numbers • What are the oxidation numbers for each atom in these compounds? UF6 : Fluorine is -1 x 6 = -6 Uranium +6 {+6 + (-6)} = 0 H2SO4 : Oxygen is -2 (x 4 = -8) Hydrogen is +1 (x 2 = +2) so Sulfur has to be +6 { (+6) + (+2) + (-8) }= 0

  43. Oxidation Numbers • What are the oxidation numbers for the chlorate polyatomic ion? ClO3- : Oxygen is -2 x 3 = -6 Chlorine must be +5 { (+5) + (-6)} = -1 (the ion’s charge)

  44. Section 4 Using Chemical Formulas

  45. Formula Mass • With a chemical formula, you can calculate many characteristic values for a compound. • Formula Mass: • Compounds have masses – just like elements.

  46. Formula Mass • Formula Mass: • The formula mass of any molecule, formula unit, or ion is the sum of the average atomic masses of all the atoms represented in its formula. • To find the mass of a compound simply add the masses of the atoms that make up the compound. Units are amu’s.

  47. Formula Mass • To find the formula mass of sulfuric acid (H2SO4): element # of atoms x mass (to 2 decimals) H 2 1.01 = 2.02 amu S 1 32.01=32.01 amu O 4 16.00=64.00 amu 98.03 amu

  48. Formula Mass • To find the formula mass of Calcium Nitrate Ca(NO3)2 element # of atoms x mass = Ca 1 40.08 =40.08 amu N 2 14.01 =28.02 amu O 6 16.00= 96.00 amu 164.10 amu

  49. Molar Mass • Molar Mass • The mass of a mole of any substance is equal to its formula mass – except instead of amu’s it is in grams. • Formula mass of sulfuric acid = 98.03 amu • Molar mass of sulfuric acid = 98.03 grams

  50. Molar Mass • To find the molar mass of Calcium Nitrate Ca(NO3)2 element # of atoms x mass = Ca 1 40.08 =40.08 g N 2 14.01 =28.02 g O 6 16.00= 96.00 g 164.10 g

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