BIO 122 Lecture Notes - Lecture 3: Covalent Bond, Hydrogen Bond, Ionic Bonding
22 Sep 2016
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Document Summary
Supernatural or divine origin (currently an untestable assumption) Life originated from inanimate materials in the primordial soup. Life most likely emerged under high-temperature conditions (120-180 degrees f) Ample availability of hydrogen atoms (reducing atmosphere) Microfossils have been found in rocks as old as 3. 5 billion years old. 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. Protons (+) and neutrons (neutral) are found on the atom"s nucleus, while electrons (-) circle the nucleus. Atoms with the same atomic number belong to the same element, and thus have the same inherent properties. An atom is the smallest unit of matter that still retains the properties of an element. The chemical behavior of an atom is determined by the distribution of elements shows the electron shells.
