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Unformatted text preview: Chapter 2: The Chemical Context of Life • Atoms – last shell determines reactivity of element • In biology, not concerned with all of periodic table o TABLE 2.1 – every living thing uses top, 99.9% use rest o Iron fourth most abundant element of earth o Elemental composition different than you’d expect is how they look for alien life forms on other planets • Isotopes – two atoms of an element that differ in number of neutrons o All atoms of an element have the same number of pronouns but different number of neutrons o Radioactive isotopes decay spontaneously giving off particle and energy o Applications of radioactive isotopes: Dating fossils Tracing atoms through metabolic processes Diagnosing medical disorders o Changing number of pronouns in an element changes it into a different element • Valence electrons are those in the outermost shell or valence shell o Behavior of atom determined by valence electrons o Full valence shells are chemically inert o Fill up valence shell and you get a noble gas...
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This note was uploaded on 09/07/2011 for the course BIOL 1201 taught by Professor Wishtichusen during the Fall '07 term at LSU.
- Fall '07