Dr. Paul Charlesworth Michigan Technological University Dr. Paul Charlesworth Michigan Technological University C h a p t e rC h a p t e r C h a p t e rC h a p t e r Chemistry, 4 th Edition McMurry/Fay Chemistry, 4 th Edition McMurry/Fay 2 2 Atoms, Molecules, and Ions

2 Atomic Theory Robert Boyle (1627–1691) Joseph Priestley (1733–1804) Antoine Lavoisier (1743–1794) Joseph Proust (1754–1826) John Dalton ( )

3 Robert Boyle Robert Boyle (1627– 1691): Provided evidence for the atoms and defined the nature of an element. More than anyone else, invented the modern experimental method.

4 Joseph Priestly Joseph Priestley (1733–1804): Isolated oxygen gas from decomposition of mercury(II) oxide. Identified 8 new gases (more than anyone else). Minister. Revolutionary.

5 Antoine Lavoisier Antoine Lavoisier (1743–1794): Showed that mass of products is exactly equal to the mass of reactants. Father of modern chemistry. Metric system. Beheaded during the revolution.

6 Conservation of Mass

7

8 Atomic Theory Law of Mass Conservation: Mass is neither created nor destroyed in chemical reactions. Law of Definite Proportions: Different samples of a pure chemical substance always contain the same proportion of elements by mass.

9 Joseph Louis Proust Joseph Louis Proust (1754–1826): Proved the law of definite proportions (sometimes called Proust’s Law). Father was an apothecary. Discovered 3 vegetable sugars.

10 Law of Definite Proportions

11 Atomic Theory Nitrogen & oxygen combine to form NO or NO 2 : In NO the N:O mass ratio is 7:8 In NO 2 the N:O mass ratio is 7:16 Hydrogen & oxygen combine to form H 2 O or H 2 O 2 : In H 2 O the H:O mass ratio is 1:8 In H 2 O 2 the H:O mass ratio is 1:16

12 Dalton’s Atomic Theory John Dalton (1766– 1844): Proposed explanations for the laws of mass conservation and definite proportions. Provided a unified atomic theory. Avid meteorologist. Worked with Nitrous Oxide and Nitrogen Dioxide.

13 Law of Multiple Proportions

14 Dalton’s Atomic Theory John Dalton (1766–1844): Proposed explanations for the laws of mass conservation and definite proportions. Postulate #1 Elements are composed of tiny particles called atoms

15 Dalton’s Atomic Theory John Dalton (1766–1844): Proposed explanations for the laws of mass conservation and definite proportions. Postulate #2 All atoms of a given element are identical having the element’s unique properties

16 Dalton’s Atomic Theory John Dalton (1766–1844): Proposed explanations for the laws of mass conservation and definite proportions. Postulate #3 Atoms are neither created nor destroyed in chemical reactions

17 Dalton’s Atomic Theory John Dalton (1766–1844): Proposed explanations for the laws of mass conservation and definite proportions. Postulate #4 Compounds are formed when atoms of more than one elenment combine. A given compound always has the same relative numbe of atoms

18 Dalton’s Atomic Theory

19 Law of Multiple Proportions: When two elements form two different compounds, the mass ratios are related by small whole numbers. Dalton’s Atomic Theory

20 Law of Multiple Proportions

21 Dalton’s Atomic Theory Methane and ethane are both constituents of natural gas. A sample of methane contains g of carbon and 3.80 g of hydrogen, whereas a sample of ethane contains 4.47 g of carbon and g of hydrogen. Show that the two substances obey the law of multiple proportions. Methane and ethane are both constituents of natural gas. A sample of methane contains g of carbon and 3.80 g of hydrogen, whereas a sample of ethane contains 4.47 g of carbon and g of hydrogen. Show that the two substances obey the law of multiple proportions.

22 The Structure of Atoms

23 The Structure of Atoms

24 The Structure of Atoms Cathode-Ray Tube (Thomson, 1856–1940): Cathode rays consist of tiny negatively charged particles, now called electrons.

25 The Structure of Atoms

27 The Structure of Atoms Deflection of electron depends on three factors: Strength of electric or magnetic field Size of negative charge on electron Mass of the electron Thomson calculated the electron’s charge to mass ratio as x 10 8 Coulombs per gram.

28 The Structure of Atoms Oil Drop Experiment (Millikan, 1868–1953): Applied a voltage to oppose the downward fall of charged drops and suspend them. Voltage on plates place x C of charge on each oil drop. Millikan calculated the electron’s mass as x grams.

29 The Structure of Atoms

30 Discovery of Nucleus (Rutherford, 1871 – 1937): Rutherford irradiated gold foil with a beam of alpha (  ) particles to search for positive charged particles. The Structure of Atoms

31 The Structure of Atoms

32 Discovery of Nucleus (Rutherford, 1871–1937): Rutherford irradiated gold foil with a beam of alpha (  ) particles to search for positive charged particles. Atom must be mostly empty space except for a central positive mass concentration. The Structure of Atoms

33 The Structure of Atoms

34 The Structure of Atoms

35 The Structure of Atoms Structure of the Atom:

36 The Structure of Atoms

37 The Structure of Atoms Atomic Mass Unit 1 amu =1/12 of the mass of on atom of Carbon-12 1 amu = x g

38 The Structure of Atoms Isotopes: Atoms with identical atomic numbers, but different mass numbers. Atomic Mass: A weighted average of the isotopic masses of an element’s naturally occurring isotopes.

39 The Structure of Atoms The isotope is used medically for diagnosis of pancreatic disorders. How many protons, neutrons, and electrons does an atom of have? An atom of element X contains 47 protons and 62 neutrons. Identify the element, and write the symbol for the isotope in the standard format Se Se

40 The Structure of Atoms Chlorine has two naturally occurring isotopes: with an abundance of 75.77% and an isotopic mass of amu, and with an abundance of 24.23% and an isotopic mass of amu. What is the atomic mass of chlorine? Cl Cl

41 The Structure of Atoms

42 Compounds and Mixtures

43 Ions Electrically charged atom or group of atoms Cation:(+) charge Anion:(-) charge Ionic Compound: A compound that consists of ions

44 Ions

45 Ions

46 Atoms, Molecules, and Ions

47 Atoms, Molecules, and Ions

48 Naming Cations 1. Elements having just one characteristic ionic charge Simply use the name of the element: Na + sodium ionZn 2+ zinc ion K + potassium ionAl 3+ aluminum ion Ca 2+ calcium ionetc.

49 Naming Cations 2. Elements forming more than one type of cation Follow the name of the element with its stock number (Roman numeral equal to the number of electrons lost): Fe 2+ iron (II) ionPb 2+ lead (II) ion Fe 3+ iron (III) ionPb 4+ lead (IV) ion

50 Naming Anions Stem + ide F - fluoride Cl - chloride Br - bromide O 2- oxide S 2- sulfide N 3- nitride

51 Naming Oxoanions Stem + ate If more than one combination exits: Stem + ate → larger number of O atoms Stem + ite → smaller number of O atoms

52 Some Common Oxoanions (NO 3 ) - nitrate (NO 2 ) - nitrite (SO 4 ) 2- sulfate (SO 3 ) 2- sulfite (PO 4 ) 3- phosphate (CO 3 ) 2- carbonate OH - hydroxide

53 Some Common Oxoanions Dichromate(Cr 2 O 7 ) 2- Permanganate(MnO 4 ) - Hydrogen Carbonate(HCO 3 ) - Bromate(BrO 3 ) - Chlorate(ClO 3 ) -

54 Polyatomic Ions

55 Ionic Compounds Ionic Bonding (Ionic Solids): These are formed by a transfer of one or more electrons from one atom to another.

56 Ionic Compounds Which of the following drawings represents an ionic compound, and which a molecular compound?

57 Ionic Compounds Main Group Cations and Anions. Ions combine to form neutral compounds. Examples: Na + and Cl – combine to form NaCl. Ca 2+ and Cl – combine to form CaCl 2. Al 3+ and Cl – combine to form AlCl 3.

58 Naming Ionic Compounds Combine Ion Names Cation + Anion NaClsodium chloride CuClcopper (I) chloride CuCl 2 copper (II) chloride CaCO 3 calcium carbonate Al 2 O 3 aluminum oxide

59 Naming Ionic Compounds If the green spheres represent cations, and the blue represent anions, which of the formulas are consistent with the figure? (a) LiBr (b) NaNO 2 (c) CaCl 2 (d) K 2 CO 3 (e) Fe 2 (SO 4 ) 3

60 Common Oxoacids

61 Molecules Covalent Bonding (Molecules): The most common type of chemical bond is formed when two atoms share some of their electrons.

62 Molecules

63 Molecule: A definite and distinct group of bonded atoms Molecular compound: A compound consisting of molecules Molecular formula: Water → H 2 0 Molecular Weight (MW): The average mass of one of the molecules of a compound. Molecules and Compounds

64 Naming Molecular Compounds MUCH more complicated! Binary compounds are often named as if they were ionic: HClhydrogen chloride CO 2 carbon dioxide

65 The Alkanes

66 The Alkanes

67 Other Interesting Compounds

68 Other Interesting Compounds