Unformatted text preview: • Water originated from volcanic activity. They produced vapor which eventually formed clouds, and then precipitation. Elements of Life • Life made up off about 25 different chemical elements. • • Carbon, hydrogen, nitrogen and oxygen make up the bulk of things. • Atoms consist of protons, neutrons, and electrons. An atom is the smallest particle of an element that retains the element’s characteristics. o Protons are positive, neutrons are neutral, and electrons are negative. o Isotopes are elements with the same number of protons, but a different number of neutrons. o Electrons are arranged in shells, which may hold varied numbers of electrons. • Atoms whose outer shells are not filled tend to react with other atoms, by losing, gaining or sharing electrons. This forms chemical bonds. o Covalent bonding shares electrons. o Hydrogen bonds are weak, but important....
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This note was uploaded on 10/05/2011 for the course BIOL 1543 taught by Professor Roberts during the Spring '08 term at Arkansas.
- Spring '08