Dear Class of 2011: Congratulations & Welcome to KAIST! Introduction to CH101H: General Chemistry I

2 Prof. Ryong Ryoo ( 유룡 교수 ) Tel: Office: Natural Science Building Rm 1106 ( 자연과학동 1106 호 ) TA: 김시인 Chem bldg Rm 문영택 Chem bldg Rm 4118

3 CH101 General Chemistry I Spring Semester 2010 Textbook: “University Chemistry” by Peter Siska (Benjamin Cummings, 2006)

General Guidelines: 4 1)You need to read the textbook before you come to the class, because it may be very difficult to understand lectures given in English during your first semester at KAIST. All basic lecture notes can be downloaded from the General Chemistry Website, or a link be found at 2)There are mandatory Quiz Sessions led by Teaching Assistants (TAs) from 7 to 7:30 pm on Mondays, after the full coverage of each chapter in the class. Quiz covers the chapter lectured in the previous week(s).

5 3)There are Practice Sessions led by TAs from 7:45 to 8:45 pm every Mondays. The Practice Sessions are not mandatory, and only those students who need extra discussions and problem-solving need to participate. 4)You should read a chapter before the chapter is started in the class, and submit your “Study Summary” of the chapter in the Quiz Session (see the lecture schedule). You have to write your Study Summary “by hand” and “in English”.

Grade Policy  pts: A+, 90-95pts: A0, 85-90pts: A-  80-85pts: B+, 75-80pts: B0, 70-75pts: B-  65-70pts: C+, 60-65pts: C0, 55-60pts: C-  50-55pts: D+, 45-50pts: D0, 40-45pts: D-  0-40pts: F  1) Mid-Term Exam: 30pts  2) Final Exam: 30pts  3) Study Summary: 10pts  4) Quiz: 10pts  5) Attendance & Attitude: 20pts (1-pt deduction for each missing class and unacceptable attitude; can be negative) 6

7 Chap1-Physical Principles Underlying Chemistry Chap2-Quantum Revolution Chap3-Wave Mechanics, Hydrogen atom Chap4-Many-Electron Atoms, Periodic Table Chap5-Valence Electron, Chemical Behavior Chap6-Valence Bond Model Chap7-Molecular Orbital Model Chap8-Molecular Motion and Spectroscopy   E=q+w sp 3 hybrid O H H

Course Schedule WeekContentNote* 1stIntroduction / Chap. 2. The Quantum Revolution Reading Assignment: Chap. 1 2ndChap. 2. The Quantum Revolution SS: Chap. 2 3rdChap. 3. Wave Mechanics and the Hydrogen Atom SS: Chap. 3 4thChap. 3. Wave Mechanics and the Hydrogen Atom Q: Chap. 2 5th Chap. 4. Atoms with Many Electrons and the Periodic Table SS: Chap. 4 6thChap. 4 / Chap. 5 Q: Chap. 3 SS: Chap. 5 7thChap. 5. Valence Electron Configurations, Periodicity, and Chemical Behavior Q: Chap. 4 8thMid-term Exam (Chap. 2 – Chap. 5) 8 *Q: the coverage of Quiz. SS:The coverage of Study Summary

9 9th Chap. 6. Orbitals and Chemical Bonding I SS: Chap. 6 10th Chap. 6. Orbitals and Chemical Bonding I 11th Chap. 7.Orbitals and Chemical Bonding II Q: Chap. 6 SS: Chap. 7 12th Chap. 7.Orbitals and Chemical Bonding II KCS ( ) 13th Chap. 8. Molecular Motion and SpectroscopySS: Chap. 8 14th Chap. 8. Molecular Motion and Spectroscopy Q: Chap. 7 15th (Chap. 8) / Review 16th Final Exam (Chap. 6 – Chap. 8)

10 What is Chemistry? Objectives of Modern Chemistry Units of Measure Force, Work, Energy Electrical Nature of Matter Nucleus, Isotopes Coulomb Force, Potential Energy e-e-

11 Chap 1. Physical Principles Underlying Chemistry 1.1 The Province of Chemistry Chemistry A branch of the natural science which deals with the material world in terms of the atomic theory of matter. A science that deals with the composition, structure, and properties of substances and with the transformations that they undergo.

is the study of matter, its structure, properties, the changes that matter undergoes, and the energy associated with these changes.

13 Role of Chemistry in Scientific Disciplines

Two distinct roots : ① Theoretical side – Early Greek philosophy ② Experimental side – Alchemy in the ancient Middle East Can be classified into Analytical, inorganic, organic, physical chemistry “Interdisciplinary” like materials chemistry Nano, Environmental, etc… Can also classified as ① Synthesis and structure of matter ② Kinetics and dynamics involved in its transformation Modern Chemistry

, Nobel Prize in Chemistry Materials: Central Role in our Modern Life ZieglerNatta

16 Nano Chemistry: New Opportunity Quantum Dots of CdSe Cluster : (2~100 molecules) Molecules m Nanopartilces: hundred~million ~10 -8 m

Carbon Allotropy: beyond our Imagination GraphiteDiamond Fullerene: C 60 Carbon Nanotubes 1996 Nobel Prize in Chemistry (Curl, Kroto, Smalley) 1991 Sumio Iijima (NEC)

Objectives of Modern Chemistry Modern chemistry – launched by R. Boyle (17c) (defining ‘element’) Elements vs. Compound or Mixture H.Cavendish (1766): hydrogen + air → water (water is not an element, but a compound) J. Priestley and A. Lavoisier established the air → a mixture of gases hydrogen + oxygen → water Lavoisier’s finding has led the law of conservation of mass

19 Law of Conservation of Mass In any physical or chemical change, mass is neither created nor destroyed. Lavoisier’s vessel (a)Hg + Air → HgO +Air The total mass has been increased (b) 2Fe + pure O 2 → 2FeO establishing conservation of mass

20 Law of Definite Proportion For a given compound, the ratio of masses between composition elements is invariable. (ex. m O /m H in water = 8:1) Law of Multiple Proportions For more than one compounds of a given pair of elements, the mass ratio of an element in both compounds is always a small whole number. (ex. the ratio between carbon dioxide and carbon monoxide = 2)

21 Atomic Theory - J. Dalton Atomic Theory - J. Dalton Law of Combining Volumes - Gay-Lussac The volumes of reacting gases are in the ratio of small whole number. The volumes of reacting gases are in the ratio of small whole number. Two volumes of hydrogen combined with one of oxygen to make two of steam.  2H 2 + O 2 → 2H 2 O H + O → HO The is composed of tiny indestructible atoms. Each element consists of tiny atoms. The matter is composed of tiny indestructible atoms. Each element consists of tiny atoms.

The Periodic Law The law (D.Mendeleyev, 1872) → organized all known elements into a table arranged by increasing mass whose columns defined chemical families

23 The Periodic Law Later, instead of atomic mass, chemists simply numbered the elements from 1 to 92: atomic number Z H. Moseley: atomic number Z (not atomic mass) is the natural ordering parameter for elements Atomic number Z: number of positive charges in nucleus

Modern Questions Identity and Composition, Structure and Reactivity 2H 2 + O 2 → 2H 2 O (1.1) 1. Why? H 2, O 2 : gases, H 2 O: liquid 2. Reaction – needs a spark to initiate - proceeds explosively with heat evolution Why the spark? 3. Nature of the bonding force of H 2 O 4. Geometry of H 2 O and geometric parameters, 5. Details of the reshuffling of atoms for the reaction We need Models  Observations  new Models

1.3 Units of Measure length, mass, time, electric charges: Fundamental physical quantities in chemistry ① cgs-esu, ② SI (Système International)

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27 Errors in Measurement Precision and accuracy – presented by the significant figures of the data (ex ±0.0001(A) vs. 3.26±0.01(B)) A: higher precisions, larger number of significant figures Precision – inherent capability of a measuring device Accuracy – closeness of the measurement to the “true” values

precise and accurate precise but not accurate Precision and accuracy in the laboratory.

systematic error random error Precision and accuracy in the laboratory.

energy due to the position of the object or energy from a chemical reaction due to a chemical state Potential Energy Kinetic Energy energy due to the motion of the object Energy Energy is the capacity to do work. Potential and kinetic energy can be interconverted. 1.4 Force, Work, and Energy

31 Temperature and Heat Energy Heat energy Mechanical energy possessed by the constituent molecules of an object. Kelvin (K) or Absolute temperature T(K) = t( 0 C) Average energy of a molecule Boltzmann’s constant

The Electrical Nature of Matter Electrical discharge tube [cation: positive ion, anion: negative..] - Cathode rays → negatively charged particle streams of electricity (electrons) emanating from the cathode (J. Thomson, 1890)

1.5 The Electrical Nature of Matter The charge-to-mass ratio q/m = x esu g -1 = x C kg -1

34 Charge-to-mass ratio of positive ions The gas in the tube is Ionized into Electron and Positive Ions Positive ions (Anode Rays !) - achieved by reversing the cathode-anode - ratio of q/m → highly dependent on the gas fill, highest value for the lightest element (H), 1836 times smaller than for the electron - For electrical neutrality, H ion carries an equal but opposite charge to that of electron with 1836 times heavier - Model for the atom (proposed by Thomson): a number of electrons and same numbers of protons

35 Millikan’s oil drop experiment The Charge on the Electron

36 Millikan’s raw expt data The Charge on the Electron

Department of Chemistry, KAIST 37 e = x esu = x C Mass of an electron m e = x g Mass of the positive ion m p = x g Millikan Library at Caltech

The Nuclear Atom Rutherford’s α-particle scattering apparatus - Experiment carried out in vacuum - Viewing microscope sealed into a rotatable hollow cylinder surrounding the stationary source and foil target - Angle-dependence of the scattering - Backward scattering - Nucleus → composed of Z protons, and ca. same numbers of neutrons in cm in dia. (J.Chadwick) out of cm of the atomic diameter. m n = x g - The same numbers, Z, of electrons → in atomic orbit.

Imagine shooting a rifle at a mound of loose snow. “You fired a 15-inch shell at a piece of tissue paper and it came back to you !!!”

41 A- Mass No. (protons + neutrons) Z- Atomic No. (protons) X-Chemical symbol Isotopes - same atomic number and different mass numbers (ex. ) Mass defect – Heavier atoms weigh < protons + electrons + neutrons → The mass converts into the binding energy (E = mc 2 ) Isotopes (Ch 16)

42 Unified mass scale relative atomic mass is assigned using C 12 isotope as the reference. AM (atomic mass)- Weighted average of natural abundances of isotopes ex. AM of carbon atom: AM(C) = (0.9890)(12.00) + (0.0110)(13.00) = 12.01

Department of Chemistry, KAIST 43

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45 Avogadro’s Number and the Mole The mass of the proton amu = x g (1 proton + 1 electron) 1 amu = x g The number of amu in a gram = x amu g -1 => This is Avogadro’s number N A g Al is special since it cancel out amu. This special g contains x atoms = 1 mol Atomic Mass of Al = amu/atom = g/mol * Exactly g of aluminum metal

Department of Chemistry, KAIST 46 Avogadro’s Number and the Mole Avogadro’s number N A no. of atoms in an atomic mass: x atoms = 1 mole Stoichiometry relations between moles in a chemical equation ex. 2H 2 + O 2 → 2 H 2 O 2 mol 1 mol 2 mol

Department of Chemistry, KAIST 47 3 Usual Ways to Calculate the number of moles 1) Pure solid or liquid: grams divided by grams/mole Al, g  2.698/26.98 = mol 2) Gas: apply the Ideal gas law (PV = nRT) 1 mole of gas: 22.4 L (1L = 1000 cm 3 = m 3 ) air bag, 2NaN 3 (s)  2Na(s) + 3N 2 (g) g(65.01 g/mol) 6.72 L 3) Solution: moles/liter = M Cola drink, sugar g/250 mL = g/L = mole

1.7 Coulomb Force and Potential Energy Coulomb’s law q 1, q 2 – charges on two bodies r – distance between them Coulomb force (or electromagnetic force) attractive q 1, q 2 – opposite sign repulsive q 1, q 2 – same sign Mutual potential energy 1 electron/1 proton system, with r 1 → ∞ ← negative of work required to pull the electron completely away from the nucleus