Lecture notes: CHEM103 Spring 2008 – September 4

SYLLABUS DISCUSSION… continued

Contact info; Office hours; WEBSITE!!!

Expectations

Assigned work (readings, problems, exams, quizzes, labs, etc.)

Attendance and grading policies

Schedule for the course – note changes already!

Recommendations for success!

Outline for the day:

· Review:

a. Define: macroscale, atomic scale

b. Identify: states of matter

· Kinetic-Molecular Theory

· States of Matter (NOW in particle scale)

· Mixtures: homogeneous vs. heterogeneous

MATTER:

a. Scale

i. Atomic-scale

ii. Macro-scale

GRAPHITE (C)

Fig. 1: Graphite is used as a control to demonstrate the resolution capabilities of the Philips 420 TEM. The periodic structure shown above represents the 3.354 Å interplanar spacing of the graphite lattice. Each lattice plane has a thickness equivalent to one carbon atom, which is 1.7 Å. The image has been averaged four times (0.33 sec exposure), normalized, scaled, and lowpass filtered for subtraction of background noise (x4,500,000). [Judith A. Sharp and R. Malcolm Brown, Jr. Department of Botany, The University of Texas at Austin]

DIAMOND (C)

The Scanning Electron Microscope (SEM) is a tool that can be used for obtaining images of surface features on diamonds. It is invaluable for resolving very fine details on diamond. [Maya Kopylova
Associate Professor Mantle Petrology, Diamonds and Diamondiferous rocks, University of British Columbia]

a. Phase (states of matter) -- MACRO-SCALE

i. Solid

maintains shape & volume

ii. Liquid

maintains volume but NOT shape

iii. Gas

Maintains NEITHER volume nor shape

KINETIC MOLECULAR THEORY (atomic-scale)

“Let the cavity contain very minute corpuscles, which are driven hither and thither with a very rapid motion, so that these corpuscles, when they strike against the piston and sustain it by their repeated impacts, form an elastic fluid which will expand of itself if the weight is removed or diminished.” – Daniel Bernoulli (1738)

Modern statement of KMT

1) infinitesimally small particles (volume occupied is negligible relative to size of container)

each have mass

assume tiny, hard spheres

2) in constant, straight-line motion; they undergo collisions w/ each other and with the walls of the container

the ONLY interactions occur at contact: there is no long-range attraction or repulsion *

all collisions are perfectly elastic – no loss of energy due to friction, etc.

3) the average kinetic energy (motion) is determined by the temperature

1/2 m v2 = KE = 3/2 kT

* we can modify this later to include particle interactions – more on this later…

1-D gas behavior: velocity and temperature

http://galileo.phys.virginia.edu/classes/109N/more_stuff/Applets/Piston/jarapplet.html

3-D gas behavior: Bernoulli’s piston

http://www.phy.ntnu.edu.tw/ntnujava/viewtopic.php?t=42

REVISIT STATES OF MATTER (phase) – but now in PARTICLE-SCALE

we will re-visit this in the “Atomic Microscope” lab…

i. Solid

ii. Liquid

iii. Gas

MIXTURES (MACROSCALE) DEMO:

i. Homogeneous mixture

ii. Heterogeneous mixture

also know the terms: suspension; colloid

KEY DIFFERENCE: “TRANSPARENT vs. COLORLESS”

examples of mixtures in Earth’s atmosphere

terms include: smoke, cloud, mist, haze