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Classifying Matter

Classifying Matter . Chapter5: Molecule & Compounds . 5.2-5.5. Day One . Polyatomic Ions . Chlorate Carbonate Phosphate Ammonium Acetate Iodate. Nitrate Cyanide Bicarbonate Sulfate Hydroxide . Law of Constant Composition. All pure substances have constant composition.

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Classifying Matter

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  1. Classifying Matter Chapter5: Molecule & Compounds

  2. 5.2-5.5 Day One

  3. Polyatomic Ions • Chlorate • Carbonate • Phosphate • Ammonium • Acetate • Iodate • Nitrate • Cyanide • Bicarbonate • Sulfate • Hydroxide

  4. Law of Constant Composition • All pure substances have constant composition. • All samples of a pure substance contain the same elements in the same percentages (ratios). • Mixtures have variable composition.

  5. Compounds Display Constant Composition If we decompose water by electrolysis, we find 16.0 grams of oxygen to every 2.00 grams of hydrogen. Water has a constant mass ratio of oxygen to hydrogen of 8.0.

  6. Why Do Compounds ShowConstant Composition? • The smallest piece of a compound is called a molecule • Every molecule of a compound has the same number and type of atoms • All the molecules of a compound are identical, every sample will have the same ratio of the elements as well as the same properties

  7. Formulas Describe Compounds • A compound is a distinct substance that is composed of atoms of two or more elements • Describe the compound by describing the number and type of each atom in the simplest unit of the compound • Molecules or ions • Each element is represented by its letter symbol • The number of atoms of each element is written as a subscript • If there is only one atom, the 1 subscript is not written • Polyatomic groups are placed in parentheses • Polyatomic ions come as packages!!! • If more than one

  8. Practice—Determine the Total Number of Atoms or Ions in One Formula Unit of Each of the Following. • Mg(C2H3O2)2 • (Hg2)3(PO4)2 1 Mg + 4 C + 6 H + 4 O = 15 6 Hg + 2 P + 8 O = 16

  9. Classifying Materials • Atomic elements = Elements whose particles are single atoms • Molecular elements(diatomic)= Elements whose particles are multi-atom molecules • Molecular compounds = Compounds whose particles are molecules made of only nonmetals. • Ionic compounds = Compounds whose particles are cations and anions.

  10. Molecular Elements • Certain elements occur as diatomic molecules. • 7 diatomic elements—The Rule of 7s • The seventh element is H2. • H O N F Cl Br I 7 N2 O2 F2 H2 Cl2 Br2 I2

  11. Molecular Compounds • Two or more nonmetals • Smallest unit is a molecule

  12. Ionic Compounds • Metals + nonmetals • No individual molecule units, instead have a 3-dimensional array of cations and anions made of formula units.

  13. Classify Each of the Following as Either an Atomic Element, Molecular Element, Molecular Compound, or Ionic Compound. • Aluminum, Al • Aluminum chloride, AlCl3 • Chlorine, Cl2 • Acetone, C3H6O • Carbon monoxide, CO • Cobalt, Co

  14. Ionic vs. Covalent Compounds IONIC • Formed from two ions • Consists of a METAL and a nonmetal or polyatomic ion • Formed from two NONMETALS COVALENT

  15. Ionic Compounds • Ionic compounds are made of ions. • Ionic compounds always contain cations and anions • Cations = + charged ions; anions = − charged ions. • The sum of the + charges of the cations must equal the sum of the − charges of the anions • The overall charge of a compound is ZERO!!

  16. Writing Formulas for IONIC Compounds • Write the elemental symbol for each element • Write the charges for each element (How do I figure this out?) • Pull the switcheroo! • Reduce subscripts to smallest whole number ratio

  17. Example • Magnesium Fluoride • Ammonium Sulfide

  18. Practice—What Are the Formulas for Compounds Made from the Following Ions? • Potassium ion with a nitride ion. • Calcium ion with a bromide ion. • Aluminum ion with a sulfide ion.

  19. Practice—What Are the Formulas for Compounds Made from the Following Ions? • Potassium ion with a sulfate ion • Calcium ion with a hydroxide • Aluminum ion with an acetate ion.

  20. Writing Formulas for Covalent (Molecular) Compounds • Write the elemental symbols for the two elements • Use the prefix to determine the subscripts for each element

  21. Greek Prefixes 1- mono 2- di 3- tri 4- tetra 5- penta 6- hexa 7- hepta 8- octa 9- nona 10- deca

  22. Let’s Try a Few • Carbon Dioxide • Dinitrogen pentaoxide • Diphosphorus trichloride

  23. Assignment • Problem Set #1 • Page 151 • #23, 31, 33, 37, 39, 41, 49, 51, 53, 70

  24. 5.6-5.8 Day Two

  25. Major Classes • Ionic compounds. • Metal + nonmetal(s). • Metal first in formula. • Binary ionic orcompounds with polyatomic ions. • Molecular compounds. • 2 or more nonmetals. • Binary molecular (or binary covalent). • 2 nonmetals. • Acids—Formula starts with H. • Though acids are molecular, they behave as ionic when dissolved in water. • May be binary or oxyacid.

  26. Classifying Compounds • Compounds containing a metal and a nonmetal = Binary ionic • Type I and II • Compounds containing a polyatomic ion = Ionic with polyatomic ion • Compounds containing two nonmetals = Binarymolecular compounds. • Compounds containing H and a nonmetal = Binary acids. • Compounds containing H and a polyatomic ion = Oxyacids.

  27. Type I Binary Ionic Compounds • Contain metal cation + nonmetal anion. • Metal listed first in formula and name. • Name metal cation first, name nonmetal anion second. • Cation name is the metal name. • Nonmetal anion named by changing the ending on the nonmetal name to –ide. Tro's "Introductory Chemistry", Chapter 5

  28. Lets try a few • KBr • MgCl2 • CaO • LiBr

  29. Type II Binary Ionic Compounds • Contain metal cation + nonmetal anion. • Metal listed first in formula and name. • Name metal cation first, name nonmetal anion second • Metal cation name is the metal name followed by a roman numeral in parentheses to indicate its charge • Determine charge from anion charge • Nonmetal anion named by changing the ending on the nonmetal name to –ide. Tro's "Introductory Chemistry", Chapter 5

  30. Practice─Name the Following Compounds. • TiCl4 • PbBr2 • Fe2S3

  31. Naming Ionic Compounds (Ternary) • Metal and a polyatomic ion • Name the metal • Name the polyatomic ion ** DO NOT CHANGE THE ENDING!!!!

  32. Let’s Try a Few • KNO3 • Mg(OH)2 • NH4NO3

  33. Covalent (Molecular) Compounds • Remember its formed from two nonmetals • Name the two elements • Add –ide to the end of the second element • Add prefixes to the elements that represent the number of atoms in the molecule

  34. Lets Try a Few • CCl4 • BCl3 • SF6 • CO

  35. Assignment • Problem Set #2 • Page 151 • #55,57,59, 61, 67, 68, 71

  36. 5.9 Day Three

  37. Polyatomic Ions List II • Bromate • Chromate • Dichromate • Permanganate • Thiosulfate

  38. Naming Polyatomic Ions • Didn’t you say we had to memorize these? • Lets look at the polyatomic ions and how they differ!!!

  39. Acids • Acids are molecular compounds that form H+ when dissolved in water • Sour taste • Dissolve many metals • Like Zn, Fe, Mg, but not Au, Ag, Pt. • Formula generally starts with H • E.g., HCl, H2SO4.

  40. Acids, Continued • Contain H+1cation and anion • In aqueous solution • Binary acids have H+1and nonmetal • Oxyacids have H+1and polyatomic

  41. Naming Binary Acids • Write a hydro- prefix. • Follow with the nonmetal name. • Change ending on nonmetal name to –ic. • Write the word acid at the end of the name.

  42. Let’s try a Few • HBr • HF • HI

  43. Naming Oxyacids

  44. Practice─Name the Following • H2S • HClO3 • HNO2

  45. Writing Formulas for Acids • When name ends in acid, formulas starts with H. • Hydro- prefix means it is binary acid, no prefix means it is an oxyacid. • For an oxyacid, if ending is –ic, polyatomic ion ends in –ate; if ending is –ous, polyatomic ion ends in –ous.

  46. Practice—What Are the Formulas for the Following Acids? • Chloricacid • Phosphoric acid • Hydrobromic acid

  47. Assignment • Problem Set #3 • Page 151 • # 73, 74, 75, 76

  48. 5.11 Day Five

  49. Tro's "Introductory Chemistry", Chapter 5

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