bio- chap 2 - I. Chemical Elements and Compounds A. Matter:...

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I. Chemical Elements and Compounds A. Matter : anything that takes up space and has mass, composes organisms 1. arises from basic ‘ingredients’ a. ancient greeks thought that basics were air, water, fire, earth 2. pure substances that could not be decomposed to other forms of matter B. Element : substance that cannot be broken down into other substances by chemical reactions 1. each has a symbol C. Compound : substance consisting of two or more elements comined in a fixed ratio 1. organized matter having emergent properties 2. compound has characteristics beyond those of its combined elements D. Life has 25 essential elements 1. 25 out of 92 elements are essential a. C, O, H, N make up 96% of living matter b. P, S, Ca, K and others make up the remaining 4% 2. Trace elements : are required by an organism in minute quantities a. Fe needed by all forms of life b. Others only required by certain species c. Vertevrates need essential element I (iodine) produced by thyroid gland. Definiency causes thyroid gland to grow to abnormal size (goiter condition), but can be reduced by iodized salt. II. Atoms (smallest unit of matter that still retains the properties of an element) and molecules A. Subatomic particles 1. Neutrons
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bio- chap 2 - I. Chemical Elements and Compounds A. Matter:...

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