BIOL 203 Study Guide - Midterm Guide: Chitin, Dynein, Cellular Respiration
Document Summary
Protons: positively charged, located in atom"s nucleus. Neutrons: neutral charge, also in nucleus, weighs the same as proton. Electrons: negative charge, located in electron cloud around nucleus, Def: a substance that can not be broken down into other substances through chemical reactions. Def: substance consisting of two or more elements in a fixed ratio. Compounds have different characteristics than the parent elements. Radioactive isotopes can be used to date fossils, trace atoms through metabolic processes, and diagnosing medical disorders. The chemical behavior of an atom mainly depends on the number of electrons in the outermost shell, called valence electrons. Covalent bonds occur when valence electrons are shared. Ionic and hydrogen bonds are considered weak chemical bonds. They are used to reinforce shapes of larger molecules, and help molecules adhere to each other. Electronegativity (en): an atom"s attraction for electrons in a covalent bond. Nonpolar bonds: between two atoms with roughly the same en, electrons equally shared.
