Humboldt State University ® Department of Chemistry

Richard A. Paselk

VUB Biology

Fall 2001

Lecture Notes:: 10 September

© R. Paselk 2001





Tentative Schedule



Who am I?


How to Study:

Course Description:


Science as a Way of Knowing

Biology is the scientific study of matter. So what do we mean by science? Two common "definitions":


Measurements & SI Units (metric system)

Significant figures: For measurements we want to be sure we convey the precision (repeatability) of our measurements using significant figures. [covered in lab & problem set] You should note a couple of aspects of significant figures:

Exponential or scientific notation: It is often convenient to express numbers in exponential or scientific notation to indicate significant figures, and to just avoid writing the huge numbers of zeros we often run into in the natural world. [covered in problem session]

SI Units: The metric system originated around the French Revolution as a rational system of measurements to rescue France from the chaos of pre-revolutionary measurements and thus prevent tax collectors from cheating.

Wanted to base system on "natural" universal standards. Thus for length they chose the size of the Earth: specifically the meter was defined as one ten-millionth (10-7) of the Earth's meridian (line from the S to the N pole) through Paris. For mass the Kilogram was defined as the mass of a cube of water 0.1 meter on a side. Of course these are not convenient, so standards were quickly created: the meter became the distance between two lines on a platinum-iridium bar stored in a vault in Paris, while the kilogram became a cylindrical mass of platinum-iridium stored in the same vault.

Today the various units are defined by international agreement to give the SI (Systéme International) units:

Prefixes: You should know (memorize) and be able to interconvert the prefixes in the table below:

Prefix Symbol Magnitude


kilo- k 103
base   100
deci- d 10-1
centi- c 10-2
milli- m 10-3
micro- m (or mc) 10-6
nano- n 10-9



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Last modified 10 September 2001
© R Paselk