BIOL 240 Lecture Notes - Lecture 2: Bombardier Beetle, Electron Shell, Enriched Uranium
Document Summary
Sodium + chlorine sodium chloride (solid + liquid salt (solid compound)) 6 essential elements (chonps) (carbon, hydrogen, oxygen, nitrogen, prosperous, sulfur) Smallest unit with the properties of an element. Atomic number: protons, and determines what the element is, it doesn"t changes. Mass number: protons + neutrons, can change, like isotopes. Same element with different # of neutrons. Can be used for: carbon dating, atomic bomb. Moving outward from atomic nucleus: energy absorbed. Moving inward from atomic nucleus : energy lost. Chemical behavior of atom depends on: valence shell, valence electrons. When atoms combine to form molecules and ionic compounds: incomplete complete valance shells, will only combine with another element that completes each other shells, full 8e- Two atoms sharing a pair of valence electrons. 2h can share bonds to become h2. Examples: hydrogen h2, oxygen o2 (double bond, water h2o, methane ch4. Attraction of a particular atom for the electrons of a covalent bond. Polar covalent bond (unequal pulling: ex.