Atomic and molecular structure Intermolecular forces & dynamics - - PowerPoint PPT Presentation

CH107 – Physical Chemistry

• Atomic and molecular structure
• Intermolecular forces & dynamics
• Driving forces for equilibrium

Instructor (D3):

• Prof. Arindam Chowdhury,

Chemistry, Room 215 Phone: x-7154; 9969437094 Email: arindam.chowdhury@gmail.com arindam@chem.iitb.ac.in

CH107/ D3 Course Information CH107/ D3 Course Information Instructor: Arindam Chowdhury Instructor: Arindam Chowdhury Room No. 215; Department of Chemistry arindam@chem.iitb.ac.in (022)2576 7154

Course Secretary: Ms. Charine Astrid Central Facility, Chemistry Department Email: charine@chem.iitb.ac.in Phone: (022)2576 4159

Attendance, marks change and course related issues:

CH-107 / D3 CH-107 / D3 23 lectures and 7 tutorials ( 23 lectures and 7 tutorials (Attendance is mandetory Attendance is mandetory) )

Lectures at Hall 1 Lectures at Hall 1 Mondays Mondays 9.30, 9.30, Tuesdays Tuesdays 10.30 and 10.30 and Thursdays Thursdays 11.30 am 11.30 am 17/09 17/09 19/09 19/09 23/09 23/09 24/09 24/09 26/09 26/09 01/10 01/10 03/10 03/10 07/10 07/10 08/10 08/10 10/10 10/10 14/10 14/10 15/10 15/10 17/10 17/10 21/10 21/10 22/10 22/10 24/10 24/10 28/10 28/10 29/10 29/10 31/10 31/10 04/11 07/11 04/11 07/11 11/11 11/11 12/11 12/11 Tutorials at Tutorials at LCT (31, 32, 33, 22, 23)

LCT (31, 32, 33, 22, 23) on

• n Mondays

Mondays 2-3 pm 2-3 pm 23/09 23/09 07/10 14/10 21/10 28/10 07/10 14/10 21/10 28/10 04/11 11/11 04/11 11/11

CH-107/D3 CH-107/D3 Tutorial venue and Teaching Assistants Tutorial venue and Teaching Assistants

D3/T1 D3/T1 LCT-31 LCT-31 Shekhar Hansda Shekhar Hansda D3/T2 D3/T2 LCT-32 LCT-32 Arindam Chowdhury Arindam Chowdhury D3/T3 D3/T3 LCT-33 LCT-33 Tuhin Khan Tuhin Khan D3/T4 D3/T4 LCT-22 LCT-22 Avinash Kumar Singh Avinash Kumar Singh D3/T5 D3/T5 LCT-23 LCT-23 Sandip Kar Sandip Kar

Emails and phone numbers to be provided Emails and phone numbers to be provided Office hours : 2 hrs/week and mutually convenient time Office hours : 2 hrs/week and mutually convenient time

CH-107 CH-107 Time Table Time Table

Duration Duration Half-semester (~8 weeks) Half-semester (~8 weeks) Quiz Quiz 19 October 2013 19 October 2013 End-Semester Exam End-Semester Exam Anywhere between 18-29 Anywhere between 18-29 November 2013 November 2013 Total Total 50 Marks 50 Marks Quiz Quiz 20 Marks 20 Marks End-Semester Exam End-Semester Exam 30 Marks 30 Marks Passing Marks Passing Marks 15 (To be followed strictly) 15 (To be followed strictly)

Evaluation Scheme Evaluation Scheme

Course Code CH 103 – SEM1 SEM1 Course Name Chemistry Total Grades Given are 416

Out of Which

AA+AB 44 BB 96 BC 95 CC 90 CD 49 DD 23 FR 19

Coursewise Statistics

Course Code CH 103 – SEM SEM2 Course Name Chemistry Total Grades Given are 452

Out of Which

AA +AB 22 BB 49 BC 71 CC 105 CD 89 DD 53 FR 63

GRADING STASTICS

Coursewise Statistics

Course Code CH 103 – SEM- SEM- 1 1 Course Name Chemistry Total Grades Given are 424

Out of Which

AA+AB 57 AP 1 BB 72 BC 83 CC 64 CD 64 DD 36 FR 47

Coursewise Statistics

Course Code CH 103 – SEM- SEM- 2 2 Course Name Chemistry Total Grades Given are 462

Out of Which

AA + AB 38 BB 49 BC 69 CC 82 CD 89 DD 48 FR 87

Coursewise Statistics

GRADING STASTICS

Why should you study Chemistry?

Is there a role of Chemistry in reshaping the modern world?

All of Science and Engineering is moving towards interdisciplinary fields of cutting-edge research!!!

 Knowing only one subject often not good enough!

• Nanoelectronics/Nanotechnology: Molecular Electronics
• Energy Science – “Solar Energy” conversion
• BioTechnology – Disease cure, health, medicine
• Atmospheric Science – Go Green - “Save the World”

Plastic Electronics and Displays

Conducting-polymers are replacing liquid crystals

Micro & Nano-electronics

1947, Transistor, Bell Labs Silicon Transistor, TI 1954 Intel, 1990s, hundreds of Transistors in a single chip Transistors, Intel, 2006, 45 nm separation Next Generation: Molecular Chips

Mechanics of Electrons and Atoms

Nano-science And Nanotechnology Mult-electron Atoms (Periodic Table) Electron Microscopy Intermolecular Forces And Interactions Multi-atomic Bonding, Molecular Structure Biology, Materials Science Condensed Matter Physics Chemical Reactions Molecular Dynamics Atomic/Molecular Spectroscopy

Contents of Part-I (14 Lectures)

• Origin of Quantization:

Lecture 1-4

Need of a new theory for electrons, atoms and molecules Postulates of Quantum Mechanics Energy Quantization: Particle in a Potential Well

• Electronic Structure in Atoms:

Lecture 5-8

Hydrogen Atom and Quantum Numbers Atomic Orbitals and Electron Densities Multi-electronic atoms and the implications of “Spin”

• Chemical Bonding:

Lectures 9-12

Molecular Orbital Theory – Linear Combination of Atomic Orbitals Energetic and electronic structure of diatomic molecules

• Molecular-Electronic structure

Lecture 13-14

Bonding in polyatomics using hybridization

Contents of Part-II (9 Lectures)

• Intermolecular Forces and PE Surfaces

Lecture 15-16

• Reaction Dynamics and Kinetic theories

Lecture 17-19

• Driving Forces for Chemical reactions

Lecture 20-21

• Chemical Potential and Equilibrium

Lecture 22-23

Recommended Text

• Physical Chemistry – I.N. Levine, 5th Ed.
• Physical Chemistry – P.W. Atkins 2nd Ed.
• Physical Chemistry: Molecular Approach -

McQuarrie and Simon Important Websites: CH107 Course Material for 2013 And previous year’s power-point slides: www.chem.iitb.ac.in/academics/menu.php and will be regularly updated in IITB Moodle http://moodle.iitb.ac.in

Classical EM theory can not explain Blackbody Radiation

Theories based on classical physics unable to explain temperature dependence of emitted radiation (radiant energy density)

Sun, stars…hot iron rod

All classical theories led to the so called “Ultraviolet Catastrophe”

2 3

8 ( ) ;

b

k T c T d d c

ν

π ρ ν ν ν ν λ = =

Max Planck assumed energies of

• scillators are discontinuous

3 /

( ) 1

v bv t

a T d e ν ρ ν = −

Assumption: Energy of electronic oscillators were discrete; Assumption: Energy of electronic oscillators were discrete; Proportional to integral multiple of frequencies Proportional to integral multiple of frequencies E = Energy of electronic oscillators v = frequency of electronic oscillators h = Planck’s constant = 6.626 x e-34 joule-sec Note: h came in as a fitting parameter

Osc

E nh ν =

1858-1947

Planck never believed his theory was right, since he was a classical physicist

3 3 /

8 ( ) 1

B

v h k T

h d T d c e ν π ν ν ρ ν

   ÷  

= −

Photoelectric Effect

• 1. Increasing intensity of light

increases number of photoelectrons, but not their max. kinetic energy (KEMAX)!

• 2. Light below a certain wavelength will not cause

ejection of electrons, no matter how high it’s intensity!

• 3. Extremely weak violet light ejects few electrons!

But their KEMax >> KEMax of electrons ejected by intense light of longer wavelength

2

( ) Wave Energy related to

• f

E E Sin kx t Intensity E Independent ω ω = − µ

Photodetectors, Photovoltaics, Elevator sensor, smoke detectors

Experimental Observations

Einstein: light behaves like particles

2

Energy to remove e' from surface

1 2

P M M

E hv KE mv KE hv φ φ φ φ

=

= = + = + = − ≥

Borrowing Planck’s idea that ∆E=hv, Einstein further proposed radiation itself existed as small packets of energy (Quanta), known as PHOTONS

P P

E E h ν ν µ =

1879-1955; Nobel prize For explanation of Photoelectric effect

Energy of photon is frequency dependent (self contradictory!)

Line Spectra of Atoms

Rydberg’s formula:

1 2 2 2 1 2

1 1 1 ;

H

R n n c n n

ν ν λ   = = = − >  ÷  

RH = 109677.57 cm-1

1854-1919

Bohr’s Phenomenological Model

(Rutherford-Planck-Einstein-Bohr Model)

• Electrons rotate in circular orbits around

a central massive nucleus (+ve), and obey laws of classical mechanics.

• Allowed orbits are those for which the

electron’s angular momentum mevr = n h/2π, n=1,2,3,4,……

• Only certain discrete energy values: “Stationary States” -

Atom in such a state does not emit EM radiation (light)

• Transition from a stationary state (Ea) to another (Eb),

atom emits or absorbs EM radiation (light)

1885-1962

Explanation of atomic spectra

n=1,2,3,... 2 (2 ) nh mvr r n π π λ = =

4 2 2 2 2

1 1 , 1,2,3,... 8

e i f i f

m e E h n n h n n ν ε   ∆ = − = =  ÷  ÷  

Spectral Transitions: ∆E=hc/λ

Explains Rydberg’s Formula

4 2 2 2

1 . 8

e n

m e E h n ε = −

Quantization of Angular momentum