물질의 구성

1. Chapter 2 물질의 구성 Unobtainium - $20 million per kg

2. 제 2장 물질의 구성 1. 원소, 화합물, 혼합물: 원자 관점에서의 개요 2. 원자설의 배경 3. 돌턴의 원자설 4. 원자핵, 전자 5. 현대의 원자론 6. 원소: 주기율표 7. 화합물과 결합 8. 화합물: 화학식, 명칭, 질량 9. 혼합물의 분류

3. Chapter 2: The Components of Matter 2.1 Elements, Compounds, and Mixtures: An Atomic Overview 2.2 The Observations That Led to an Atomic View of Matter 2.3 Dalton’s Atomic Theory 2.4 The Observations That Led to the Nuclear Atom Model 2.5 The Atomic Theory Today 2.6 Elements: A First Look at the Periodic Table 2.7 Compounds: Introduction to Bonding 2.8 Compounds: Formulas, Names, and Masses 2.9 Classification of Mixtures

4. Definitions for Components of Matter Element - the simplest type of substance with unique physical and chemical properties. An element consists of only one type of atom. It cannot be broken down into any simpler substances by physical or chemical means. Molecule - a structure that consists of two or more atoms that are chemically bound together and thus behaves as an independent unit. Figure 2.1

5. Definitions for Components of Matter Compound - a substance composed of two or more elements which are chemically combined. Figure 2.1 Mixture - a group of two or more elements and/or compounds that are physically intermingled.

7. 고전적 견해원자설 이전 Law of Conservation of Mass In Reflexions sur le Phlogistique (1783), Antoine Lavoisier Law of the Definite Proportions Joseph-Louise Proust Proust's Law(1799) <=> Pierre Berthollet Law of Multiple Proportions Dalton(1803) 원자설의 배경

8. total mass total mass calcium oxide + carbon dioxide calcium carbonate CaO + CO2 CaCO3 Law of Mass Conservation: The total mass of substances does not change during a chemical reaction. reactant 1 + reactant 2 product = 56.08g + 44.00g 100.08g

9. 8.0 g calcium 2.4 g carbon 9.6 g oxygen 0.40 calcium 0.12 carbon 0.48 oxygen 40% calcium 12% carbon 48% oxygen 20.0 g 1.00 part by mass 100% by mass Law of Definite (or Constant) Composition: No matter the source, a particular compound is composed of the same elements in the same parts (fractions) by mass. Calcium carbonate Analysis by Mass (grams/20.0g) Mass Fraction (parts/1.00 part) Percent by Mass (parts/100 parts)

10. mass(kg) uranium in pitchblende mass(kg) pitchblende 71.4kg uranium 84.2kg pitchblende 1000g kg Calculating the Mass of an Element in a Compound Pitchblende is the most commercially important compound of uranium. Analysis shows that 84.2 g of pitchblende contains 71.4 g of uranium, with oxygen as the only other element. How many grams of uranium can be obtained from 102 kg of pitchblende? SOLUTION: mass (kg) of uranium = mass(kg) pitchblende x = 86.5 kg uranium = 102 kg pitchblende x 86.5 kg uranium x = 8.65 x 104g uranium

11. g O g O 72.7 57.1 g C g C = 27.3 42.9 = 1.33 2.66 g O/g C in II 2 = 1.33 g O/g C in I 1 = 2.66 Law of Multiple Proportions: If elements A and B react to form two compounds, the different masses of B that combine with a fixed mass of A can be expressed as a ratio of small whole numbers. Example: Carbon Oxides A & B Carbon Oxide I : 57.1% oxygen and 42.9% carbon Carbon Oxide II : 72.7% oxygen and 27.3% carbon Assume that you have 100g of each compound. In 100 g of each compound: g O = 57.1 g for oxide I & 72.7 g for oxide II g C = 42.9 g for oxide I & 27.3 gfor oxide II =

12. Dalton’s Atomic Theory The Postulates 1. All matter consists of atoms. 2. Atoms of one element cannot be converted into atoms of another element. 3. Atoms of an element are identical in mass and other properties and are different from atoms of any other element. 4. Compounds result from the chemical combination of a specific ratio of atoms of different elements.

13. Dalton’s Atomic Theory Mass conservation Atoms cannot be created or destroyed postulate 1 or converted into other types of atoms. postulate 2 postulate 3 Since every atom has a fixed mass, during a chemical reaction atoms are combined differently and therefore there is no mass change overall.

14. Dalton’s Atomic Theory Definite composition Atoms are combined in compounds in specific ratios postulate 3 and each atom has a specific mass. postulate 4 So each element has a fixed fraction of the total mass in a compound.

15. Dalton’s Atomic Theory Multiple proportions Atoms of an element have the same mass postulate 3 and atoms are indivisible. postulate 1 So when different numbers of atoms of elements combine, they must do so in ratios of small, whole numbers. Figure 2.3

16. Thomson's first experiment Cathode rays pass from the tube in the upper left into the larger bulb, where they are deflected with a magnetic field. When they are bent so as to enter the slits in the cylinders, the electrometer measures the charge transferred to the cylinder. J.J. Thomson, "Cathode Rays," The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, Fifth Series, October 1897. p. 295

17. Thomson's second experiment Rays from the cathode (C) pass through a slit in the anode (A) and through a slit in a grounded metal plug (B). An electrical voltage is established between aluminum plates (D and E), and a scale pasted on the outside of the end of the tube measures the deflection of the rays. J.J. Thomson, "Cathode Rays," The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, Fifth Series, October 1897. p. 296

18. Thomson's third experiment Rays originate at the cathode on the left and pass through a slit in the anode into a bell jar containing gas at low pressure. The deflected paths of the rays are photographed against a ruled glass plate. J.J. Thomson, "Cathode Rays," The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, Fifth Series, October 1897. p. 301

19. with external magnetic field with external magnetic and electric field S l L <플레밍의 왼손법칙> with external electric field B i F J.J. Thomson, measured mass/charge of e-(1897) (1906 Nobel prize in physics)

20. Experiments to Determine the Properties of Cathode Rays Thomson’s plum pudding model of the atom

21. (1909) Measured of e-charge (1923 Nobel Prize in physics) e- charge = -1.60 x 10-19 C Thomson’s charge/mass of e- = -1.76 x 108 C/g e- mass = 9.10 x 10-28 g

22. determined by J.J. Thomson and others mass charge mass of electron = × charge Millikan used his findings to also calculate the mass of an electron. = (-5.686×10-12kg/C) ×(-1.602×10-19C) = 9.109×10-31kg = 9.109×10-28g

23. Geiger–Marsden experiment(1909)and Rutherford’s interpretation(1911) • particle velocity ~ 1.4 x 107 m/s (~5% speed of light) • atoms positive charge is concentrated in the nucleus • proton (p) has opposite (+) charge of electron (-) • mass of p is 1840 x mass of e- (1.67 x 10-24 g)

24. Geiger–Marsden experiment(1909)and Rutherford’s interpretation(1911) • The expected result of the Rutherford's αparticle scattering experiment, assuming the Thomson’s model. • (b) The result of the Rutherford's αparticle scattering experiment It was quite the most incredible event that has ever happened to me in my life. It was almost as incredible as if you fired a 15-inch shell at a piece of tissue paper and it came back and hit you. ... It was then that I had the idea of an atom with a minute massive centre, carrying a charge.—Ernest Rutherford, Nobel prize in chemistry, 1908 for "for his investigations into the disintegration of the elements, and the chemistry of radioactive substances"

25. a+ 9Be 1n + 12C + energy Chadwick’s Experiment (1932)(1935 Noble Prize in physics) H atoms - 1 p; He atoms - 2 p mass He/mass H should = 2 measu4 mass He/mass H = 4 neutron (n) is neutral (charge = 0) n mass ~ p mass = 1.67 x 10-24 g 2.2

26. HeliumAtom “원자가 반지름이 100m인 운동장 만하다면, 핵은 운동장 중심에 있는 반지름이 수mm인 작은구슬 정도의 크기이다.”

27. Properties of the Three Key Subatomic Particles † The atomic mass unit (amu) equals 1.66054x10-27 kg.

28. A X Mass Number Element Symbol Z Atomic Number 1 2 3 H (D) H (T) H 1 1 1 235 238 U U 92 92 Atomic number, Mass number and Isotopes Atomic number (Z) = number of protons in nucleus Mass number (A) = number of protons + number of neutrons = atomic number (Z) + number of neutrons Isotopes are atoms of the same element (X) with different numbers of neutrons in their nuclei 2.3

29. The Mass Spectrometer and Its Data 0 -V acceleration M+ Ion Generation R Mass Selection 20Ne 21Ne 22Ne

30. Determining the Number of Subatomic Particles in the Isotopes of an Element Silicon(Si) is essential to the computer industry as a major component of semiconductor chips. It has three naturally occurring isotopes: 28Si, 29Si, and 30Si. Determine the number of protons, neutrons, and electrons in each silicon isotope. SOLUTION: The atomic number of silicon is 14. Therefore 28Si has 14p+, 14e- and 14n0 (28-14) 29Si has 14p+, 14e- and 15n0 (29-14) 30Si has 14p+, 14e- and 16n0 (30-14)

31. Silver(Ag: Z = 47) has 46 known isotopes, but only two occur naturally, 107Ag and 109Ag. Given the following mass spectrometric data, calculate the atomic mass of Ag: Isotope Mass(amu) Abundance(%) 107Ag 106.90509 51.84 109Ag 108.90476 48.16 Calculating the Atomic Mass of an Element SOLUTION: weighted average of the isotopic masses 106.90509amu ×0.5184 + 108.90476amu × 0.4816 =107.87amu

32. The Modern Reassessment of the Atomic Theory 1. All matter is composed of atoms. The atom is the smallest body thatretains the unique identityof the element. 2. Atoms of one element cannot be converted into atoms of another element in a chemical reaction. Elements can only be converted into other elements in nuclear reactions. 3. All atoms of an element have the same number of protons and electrons, which determines the chemical behavior of the element. Isotopes of an element differ in the number of neutrons, and thus in mass number. A sample of the element is treated as though its atoms have anaverage mass. 4. Compounds are formed by the chemical combination of two or more elements in specific ratios.

33. The modern periodic table. Figure 2.10

34. 11 p+ 11 e – 11 p+ 10 e– Na Na+ 17 p+ 17 e– 17 p+ 18 e– Cl– Cl The formation of an ionic compound An ion is an atom, or group of atoms, that has a net positive or negative charge. cation – ion with a positive charge If a neutral atom loses one or more electrons it becomes a cation. → + 1e– sodium ion sodium anion – ion with a negative charge If a neutral atom gains one or more electrons it becomes an anion. → + 1e– chlorine chloride ion 2.5

35. Factors that influence the strength of ionic bonding. coulomb attraction

36. I- Iodine is a nonmetal in Group 7A(17). It gains one electron to have the same number of electrons as 54Xe. Ca2+ Calcium is a metal in Group 2A(2). It loses two electrons to have the same number of electrons as 18Ar. Al3+ Aluminum is a metal in Group 3A(13). It loses three electrons to have the same number of electrons as 10Ne. Pridictingthe Ion and Element Forms What monatomic ions do the following elements form? (a) Iodine (Z = 53) (b) Calcium (Z = 20) (c) Aluminum (Z = 13) SOLUTION:

37. Formation of a covalent bond between two H atoms. Figure 2.13 Covalent bonds form when elements share electrons, which usually occurs between nonmetals.

38. Elements that occur as molecules. diatomic molecules tetratomic molecules octatomic molecules

39. Figure 2.15 Elements that are polyatomic. A polyatomic ion

40. Types of Chemical Formulas A chemical formula is comprised of element symbols and numerical subscripts that show the type and number of each atom present in the smallest unit of the substance. An empirical formula indicates the relative number of atoms of each element in the compound. It is the simplest type of formula. The empirical formula for hydrogen peroxide is HO. A molecular formula shows the actual number of atoms of each element in a molecule of the compound. The molecular formula for hydrogen peroxide is H2O2. A structural formula shows the number of atoms and the bonds between them, that is, the relative placement and connections of atoms in the molecule. The structural formula for hydrogen peroxide is H-O-O-H.

41. Noble Gas Alkali Earth Metal Halogen Alkali Metal Some common monatomic ions of the elements. Figure 2.16 Can you see any patterns?

42. Table 2.3 Common Monoatomic Ions Common ions are in 2. Cations Anions

43. cation + anion anion (nonmetal), add suffix “-ide” to element root Chemical Nomenclature Ionic Compounds barium chloride 염화 바륨 BaCl2 potassium oxide 산화 포타슘 K2O magnesium hydroxide 수산화 마그네슘 Mg(OH)2 potassium nitrate 질산 포타슘 KNO3 • 음이온 (비금속), 접미사 “-화” • 음이온 + 양이온 2.7

44. Binary Ionic Compounds Write empirical formulas for the compounds formed from the following pairs of elements, and name them: (a) magnesium and nitrogen (b) iodine and cadmium (c) strontium and fluorine (d) sulfur and cesium SOLUTION: (a) magnesium nitride (a) Mg2+ and N3–; three Mg2+(6+) and two N3– (6-); Mg3N2 (b) cadmium iodide (b) Cd2+ and I–; one Cd2+(2+) and two I– (2-); CdI2 (c) strontium fluoride (c) Sr2+ and F–; one Sr2+(2+) and two F– (2-); SrF2 (d) cesium sulfide (d) Cs+ and S2–; two Cs+(2+) and one S2– (2-); Cs2S

45. Copper Cu+ copper(I) cuprous Cu2+ copper(II) cupric Co2+ cobalt(II) Cobalt Co3+ Fe2+ cobalt (III) iron(II) ferrous Iron Fe3+ iron(III) ferric Mn2+ manganese(II) Manganese Mn3+ manganese(III) Sn2+ tin(II) stannous Tin Sn4+ tin(IV) stannic Metals With Several Oxidation States Element Ion Formula Systematic Name Common Name

46. Give the systematic names for the formulas or the formulas for the names of the following compounds: (a) tin(II) fluoride (b) CrI3 (d) CoS (c) ferric oxide Determining Names and Formulas of Ionic Compounds of Elements That Form More Than One Ion SOLUTION: (a) Tin (II) is Sn2+; fluoride is F –; so the formula is SnF2. (b) The anion I is iodide(I–); 3I- means that Cr(chromium) is +3. CrI3 is chromium(III) iodide (c) Ferric is a common name for Fe3+; oxide is O2–, therefore the formula is Fe2O3. (d) Co is cobalt; the anion S is sulfide(S2–); the compound is cobalt (II) sulfide.

47. Some Common Polyatomic Ions Cations Common Anions

48. 2.7

49. Don’t confuse with

50. Molecular compounds • nonmetals or nonmetals + metalloids • common names • H2O, NH3, CH4, C60 • element further left in periodic table is 1st • element closest to bottom of group is 1st • if more than one compound can be formed from the same elements, use prefixes to indicate number of each kind of atom • last element ends in -ide HI hydrogen iodide NF3 nitrogen trifluoride SO2 sulfur dioxide dinitrogentetrachloride N2Cl4 NO2 nitrogen dioxide N2O dinitrogenmonoxide