BIO 121 Chapter Notes - Chapter 2: Radionuclide, Atomic Nucleus, Radiometric Dating
11 Apr 2017
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Matter consists of chemical elements in pure form and in combinations called compounds (2. 1) Matter: anything that takes up space and has mass. Element: a substance that can not be broken down into other substances by chemical rxns. Compound: a substance consisting of 2+ elements combined in a fixed ratio (1:1) Organisms are composed of matter and matter is made up of elements. 92 elements occurring in nature: essential elements: of the 92 natural elements, 20-25% of them are needed by organisms in order to live a healthy life and reproduce. O, c, h, and n make up 96% of living matter. Ca, p, k, and s make up the remaining 4% (with other trace elements, elements requires by organisms in small quantitits, like iron) An elements properties depend on the structure of its atoms (2. 2) Atom: smallest unit of matter that still retains the properties of an element, and consists of subatomic particles neutrons, protons, electrons.
