Biology Chapter 2 Notes

Biology Chapter 2 Notes - Chapter 2 The Chemical Context of...

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Overview: A Chemical Connection to Biology Biology is a multidisciplinary science Living organisms are subject to basic laws of physics and chemistry One example is the use of formic acid by ants to maintain “devil’s gardens,” stands of Duroia trees Concept 2.1: Matter consists of chemical elements in pure form and in combinations called compounds Organisms are composed Matter is anything that takes up space and has mass Elements and Compounds Matter is made up of elements An element is a substance that cannot be broken down to other substances by chemical reactions A compound is a substance consisting of two or more elements in a fixed ratio - A compound has characteristics different from those of its elements The Elements of Life About 20-25% the 92 elements are essential to life Carbon, hydrogen, oxygen, and nitrogen make up 96% of living matter Most of the remaining 4% of calcium, phosphorus, potassium, and sulfur - Trace Elements are those required by an organism in minute quantities Concept 2.2: An element’s properties depend on the structure of its atoms Each element consists of unique atoms - An atom is the smallest unit of matter that still retains the properties of an element Subatomic Particles Atoms are composed of subatomic particles Relevant subatomic particles include Neutrons (no electrical charge) Protons (positive charge) Electrons (negative charge) Neutrons and protons form the atomic nucleus Electrons form a cloud around the nucleus Neutron mass and proton mass are almost identical and are measured in Daltons Atomic Number and Atomic Mass Atoms of the various elements differ in number of subatomic particles An element’s atomic number is the number of protons in its nucleus An element’s mass number is the sum of protons plus neutrons in the nucleus
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This note was uploaded on 10/04/2011 for the course BIOLOGY 1305 taught by Professor Adair during the Fall '09 term at Baylor.

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Biology Chapter 2 Notes - Chapter 2 The Chemical Context of...

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