09 16 09 Notes

Biology and Human Concerns 09/16/09 – Notes Basic Chemistry (Chapter Two) Chemical Elements Element => substance that cannot be broken down to other substances by chemical reactions Compound => substance consisting of two or more elements combined in a fixed ratio. Water = H2O two hydrogen atoms affixed to an oxygen atom Sodium + Chlorine = sodium chloride = table salt Atoms and Molecules Subatomic particles: -Neutrons -Protons (ex. Bowling ball) -Electrons (ex. Ping pong ball) Atomic Number -the number of protons Atomic Mass (Mass number) -Neutrons plus Protons --Same charges repel, opposite charges attract— page 20 Isotopes -Some atoms of a given element have more neutrons than others ex. 12C is the most common form of carbon, stable. 13C also stable. 14 C is an unstable “radioactive isotope” of carbon (heavier)

-Radioactive tracer used to determine how much DNA is made at different temperatures Diagram on page 22—partial periodic table

09 16 09 Notes

by kerri035 on Dec 03, 2009

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09 16 09 Notes Document Transcript