Biology 101B
19 January, 1998
Life
on Planet Earth
Chapter
2B - Introduction to Science:Chemistry
I. Matter
and Energy
II. The Structure
of Matter
III. Chemical
Bonds: Joining Atoms to Make Molecules
III. Organic
and Inorganic Molecules
V. Water
and Life
The
Creation
of Matter
and Energy
This is picture of the Infrared
heat left from the "Big Bang", about 15,000,000,000 years ago.
I. Matter and Energy
-
Energy exists in several forms that can be interconverted.
II. The Structure of Matter 
-
Atoms, the smallest units of elements, are composed of still
smaller particles.
![[image]](05med.gif)
Atoms on a Silicon Surface
Scanning tunneling micrograph, about 1,000,000,000X
Russell Becker
Measuring less than 1/100,000,000th of an inch, the hills in this micrograph
are individual atoms on a silicon crystal that have been enlarged more
than one billion times. A Scanning Tunneling Microscope collects digital
information which is plotted by a computer. Colors are false colors assigned
by the computer to help researchers see how crystalline structures are
formed.
Photo credit:
AT&T
-
Atoms will react with other atoms only when there are vacancies
in their outermost electron shells.
III. Chemical Bonds: Joining Atoms
to Make Molecules
-
Atoms can become stable by gaining or losing electrons, forming
charged ions; the attraction between oppositely charged ions produces ionic
bonds.
-
Atoms can become stable by sharing electrons with other atoms,
forming covalent bonds.
-
Hydrogen bonds are weak electrical attractions between the
polar parts molecules.
IV. Organic and Inorganic Molecules
Generally, Organic molecules contain
Carbon, and can be quite large,
consisting of up to millions of
atoms.
Inorganic molecules do not have
any carbon, and are usually much smaller, often containing only a few atoms.
V. Water and Life 
-
Water interacts with many other molecules.
-
The pH of a solution is a measure of its concentration of
hydrogen ions.
-
A buffer helps maintain a solution at a relatively constant
pH.
-
Water forms an unusual solid, ice.
-
Water molecules tend to stick together.
Here are some pictures of atoms:
Atoms can be manipulated, using nanotechnology, into specific positions:
This person is LITERALLY made of atoms!
Click
here to go to the MicroScapes Gallery
Back to the Biology 101 Syllabus
Last modified on: 31 January, 2000 by Dave Ussery