Presentation is loading. Please wait.

Presentation is loading. Please wait.

Chapter Two: ATOMS, MOLECULES, AND IONS. Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 2 Early History of Chemistry Greeks.

Similar presentations


Presentation on theme: "Chapter Two: ATOMS, MOLECULES, AND IONS. Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 2 Early History of Chemistry Greeks."— Presentation transcript:

1 Chapter Two: ATOMS, MOLECULES, AND IONS

2 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 2 Early History of Chemistry Greeks were the first to attempt to explain why chemical changes occur. Alchemy dominated for 2000 years: –Several elements discovered –Mineral acids prepared Robert Boyle was the first chemist: –Performed quantitative experiments 2.1

3 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 3 Three Important Laws Law of conservation of mass (Lavoisier): –Mass is neither created nor destroyed Law of definite proportion (Proust): –A given compound always contains exactly the same proportion of elements by mass 2.2

4 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 4 Three Important Laws (continued) Law of multiple proportions (Dalton): –When two elements form a series of compounds, the ratios of the masses of the second element that combine with 1 gram of the first element can always be reduced to small whole numbers –http://cwx.prenhall.com/petrucci/medialib/medi a_portfolio/text_images/003_MULTIPLEPROP. MOVhttp://cwx.prenhall.com/petrucci/medialib/medi a_portfolio/text_images/003_MULTIPLEPROP. MOV 2.2

5 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 5 Daltons Atomic Theory (1808) Each element is made up of tiny particles called atoms. 2.3

6 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 6 Daltons Atomic Theory (continued) The atoms of a given element are identical; the atoms of different elements are different in some fundamental way or ways. 2.3

7 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 7 Daltons Atomic Theory (continued) Chemical compounds are formed when atoms of different elements combine with each other. A given compound always has the same relative numbers and types of atoms. 2.3

8 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 8 Daltons Atomic Theory (continued) Chemical reactions involve reorganization of the atomschanges in the way they are bound together. The atoms themselves are not changed in a chemical reaction. 2.3

9 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 9 Concept Check Which of the following statements regarding Daltons atomic theory are still believed to be true? I. Elements are made of tiny particles called atoms. II. All atoms of a given element are identical. III. A given compound always has the same relative numbers and types of atoms. IV. Atoms are indestructible.

10 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 10 Early Experiments to Characterize the Atom J. J. Thomson ( ): –Postulated the existence of electrons using cathode-ray tubes –Determined the charge-to-mass ratio of an electron –The atom must also contain positive particles that balance exactly the negative charge carried by the electrons 2.4

11 Figure 2.8 Deflection of Cathode Rays by an Applied Electric Field

12 Figure 2.9 The Plum Pudding Model of the Atom

13 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 13 Early Experiments to Characterize the Atom Robert Millikan (1909): –Performed experiments involving charged oil drops –Determined the magnitude of the electron charge –Calculated the mass of the electron 2.4

14 Figure 2.10 A Schematic Representation of the Apparatus Millikan Used to Determine the Charge on the Electron

15 Milikans Experiment edia_portfolio/text_images/004_MILLIKAN OIL.MOVhttp://cwx.prenhall.com/petrucci/medialib/m edia_portfolio/text_images/004_MILLIKAN OIL.MOV Perform Millilkans Experiment yourself –http://webphysics.davidson.edu/applets/pqp_pr eview/contents/pqp_errata/cd_errata_fixes/sec tion4_5.htmlhttp://webphysics.davidson.edu/applets/pqp_pr eview/contents/pqp_errata/cd_errata_fixes/sec tion4_5.html Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 15

16 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 16 Early Experiments to Characterize the Atom Ernest Rutherford (1911): –Explained the nuclear atom –Atom has a dense center of positive charge called the nucleus –Electrons travel around the nucleus at a relatively large distance 2.4

17 Figure 2.12 Rutherford's Experiment On a- Particle Bombardment of Metal Foil

18 Rutherfords experiment a/rutherford/http://micro.magnet.fsu.edu/electromag/jav a/rutherford/ Animation with narration –http://cwx.prenhall.com/petrucci/medialib/medi a_portfolio/text_images/006_RUTHERFORD. MOVhttp://cwx.prenhall.com/petrucci/medialib/medi a_portfolio/text_images/006_RUTHERFORD. MOV Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 18

19 Rutherfords Observations Most α particles passed straight through the foil Some α particles were deflected to the side A few α particles were bounced backward Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 19

20 Figure 2.13 a & b (a) Expected Results of the Metal Foil Experiment if Thomson's Model Were Correct (b) Actual Results

21 Rutherfords Conclusions Atoms are mostly empty space Atoms contain positively charged particles Atoms contain a dense nucleus Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 21

22 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 22 The Modern View of Atomic Structure- Nuclear Model The atom contains: Electrons Protons – found in the nucleus; positive charge equal in magnitude to the electrons negative charge Neutrons – found in the nucleus; no charge; virtually same mass as a proton 2.5

23 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 23 The Modern View of Atomic Structure The nucleus is: –Small compared with the overall size of the atom –Extremely dense; accounts for almost all of the atoms mass 2.5

24 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 24 Nuclear Atom Viewed in Cross Section

25 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 25 The Modern View of Atomic Structure Isotopes: –Atoms with the same number of protons but different numbers of neutrons –Show almost identical chemical properties; chemistry of atom is due to its electrons –In nature most elements contain mixtures of isotopes 2.5

26 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 26 Two Isotopes of Sodium 2.5

27 Isotope Symbols X = Element symbol Z = Atomic Number = number of protons A = Mass Number = protons + neutrons Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 27

28 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 28 Exercise A certain isotope X contains 54 electrons and 78 neutrons. What is the mass number of this isotope? What is the symbol of this isotope? 2.5/2.6

29 Ions Atoms that have gained or lost electrons Gained electrons –Negative charge –Anion Lost electrons –Positive charge –Cation Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 29

30 Cations Mg 2+ –Lost 2 electrons K + –Lost 1 electron Anions F - –Gained 1 electron S 2- –Gained 2 electrons Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 30

31 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 31 Chemical Bonds Covalent Bonds: –Bonds form between atoms by sharing electrons –Resulting collection of atoms is called a molecule 2.6

32 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 32 Covalent Bonding 2.6

33 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 33 Chemical Bonds Ionic Bonds: Bonds form due to force of attraction between oppositely charged ions Ion – atom or group of atoms that has a net positive or negative charge Cation – positive ion; lost electron(s) Anion – negative ion; gained electron(s) 2.6

34 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 34 Molecular vs. Ionic Compounds 2.6

35 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 35 The Periodic Table Metals vs. Nonmetals Groups or Families – elements in the same vertical columns –Alkali metals, alkaline earth metals, halogens, and noble gases Periods – horizontal rows of elements 2.7

36 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 36 The Periodic Table 2.7

37 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 37 Naming Compounds Binary Compounds: –Composed of two elements Binary Ionic Compounds: –Metal-nonmetal Binary Covalent Compounds: –Nonmetal to nonmetal 2.8

38 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 38 Binary Ionic Compounds (Type I) Cation is always named first and the anion second. Monatomic cation has the same name as its parent element. Monatomic anion is named by taking the root of the element name and adding –ide. 2.8

39 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 39 Binary Ionic Compounds (Type I) Examples: KClPotassium chloride MgBr 2 Magnesium bromide CaOCalcium oxide 2.8

40 Chemical Formulas Identify the elements present –Element symbols Identify the number of each atom –Subscripts Aluminum sulfideAl 2 S 3 –2 Al atoms for every 3 S atoms

41 Writing the Formulas from the Names –Determine the ions present –Determine the charges on the cation and anion –Balance the charges to get the subscripts

42 Writing the Formulas from the Names (cont.) Magnesium chloride –Mg 2+ Cl - –Total positive charge must equal total negative charge –1 Mg 2+ will balance 2Cl - –MgCl 2

43 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 43 Polyatomic Ions Ions consisting of two or more covalently bonded atoms Examples of compounds containing polyatomic ions: NaOHSodium hydroxide Mg(NO 3 ) 2 Magnesium nitrate (NH 4 ) 2 SO 4 Ammonium sulfate 2.8

44 Compounds Containing Polyatomic Ions Polyatomic ions are charged entities that contain more than one atom Polyatomic compounds contain one or more polyatomic ions Name polyatomic compounds by naming cation and anion Al(C 2 H 3 O 2 ) 3 = aluminum acetate

45 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 45 Binary Ionic Compounds (Type II) Metals in these compounds form more than one type of positive charge. Charge on the metal ion must be specified. Roman numeral indicates the charge of the metal cation. Transition metal cations usually require a Roman numeral. 2.8

46 Determining the Charge on a Cation – Au 2 S 3 Determine the charge on the anion –Sulfide = -2 Determine the total negative charge –(-2) x 3 = -6 Total positive charge = total negative charge Divide total positive charge by the number of cations –+6/2 = +3

47 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 47 Binary Ionic Compounds (Type II) Examples: CuBrCopper(I) bromide FeSIron(II) sulfide PbO 2 Lead(IV) oxide 2.8

48 Type II Binary Ionic Compounds (cont.) ¶Old naming system ¶Uses root name or latin name for metal ¶Uses suffixes instead of roman numerals

49 Type II Binary Ionic Compounds (cont.) ¶Suffixes ¶_____ic for higher charge ¶_____ous for lower charge

50 Type II Binary Ionic Compounds (cont.) ¶Examples ¶Iron (III) chloride = ferric chloride ¶Iron (II) chloride = ferrous chloride

51 Type II Binary Ionic Compounds (cont.) ¶Common latin names ¶Cu – cupric, cuprous ¶Pb – plumbic, plumbous ¶Sn – stannic, stannous ¶Fe – ferric, ferrous

52 Writing the Formulas from the Names (cont.) For Type II Determine the charges on the cation and anion Charge on cation = roman numeral –Balance the charges to get the subscripts

53 Writing the Formulas from the Names (cont.) Copper (I) oxide –Cu +1 O -2 –2 Cu +1 will balance 1 O -2 –Cu 2 O

54 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 54 Formation of Ionic Compounds 2.8

55 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 55 Binary Covalent Compounds (Type III) Formed between two nonmetals. First element is named first, using the full element name. Second element is named as if it were an anion. Prefixes are used to denote the numbers of atoms present. Prefix mono- is never used for naming the first element. 2.8

56 Table 2.6 Prefixes Used to Indicate Number in Chemical Names

57 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 57 Binary Covalent Compounds (Type III) Examples: CO 2 Carbon dioxide SF 6 Sulfur hexafluoride N 2 O 4 Dinitrogen tetroxide 2.8

58 Writing the Formulas from the Names For Type III compounds, use the prefixes to determine the subscripts Carbon tetrachloride = CCl 4

59 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 59 Overall Strategy for Naming Chemical Compounds

60 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 60 Flowchart for Naming Binary Compounds

61 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 61 Acids Acids can be recognized by the hydrogen that appears first in the formulaHCl. Molecule with one or more H + ions attached to an anion. 2.8

62 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 62 Acids If the anion does not contain oxygen, the acid is named with the prefix hydro- and the suffix -ic. Examples: HClHydrochloric acid HCNHydrocyanic acid H 2 SHydrosulfuric acid 2.8

63 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 63 Acids If the anion does contain oxygen: –The suffix -ic is added to the root name if the anion name ends in -ate. Examples: HNO 3 Nitric acid H 2 SO 4 Sulfuric acid HC 2 H 3 O 2 Acetic acid 2.8

64 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 64 Acids If the anion does contain oxygen: –The suffix -ous is added to the root name if the anion name ends in -ite. Examples: HNO 2 Nitrous acid H 2 SO 3 Sulfurous acid HClO 2 Chlorous acid 2.8

65 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 65 Flowchart for Naming Acids

66 Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 66 Exercise Which of the following compounds is named incorrectly? a) KNO 3 potassium nitrate b) TiO 2 titanium(II) oxide c) Sn(OH) 4 tin(IV) hydroxide d) PBr 5 phosphorus pentabromide e) CaCrO 4 calcium chromate 2.8


Download ppt "Chapter Two: ATOMS, MOLECULES, AND IONS. Copyright © Houghton Mifflin Company. All rights reserved. Chapter 2 | Slide 2 Early History of Chemistry Greeks."

Similar presentations


Ads by Google