BIOL 235 Chapter Notes - Chapter 2: Electron Shell, Atomic Mass, Mass Number
Document Summary
Chapter 2 the chemical level of organization. Atomic number and mass number: atomic number: number of protons, mass number: number of protons and neurons. Isotopes: atoms of an element that have different numbers of neutrons and therefore different mass numbers. Atomic mass: dalton: standard unit for measuring the mass of atoms and their sub- atomic particles, atomic mass: average mass of all its naturally occurring isotopes, typically close to the mas number. Ions, molecules, and compounds: the atoms of each element have a characteristic way of losing, gaining, or sharing their electrons when interacting with other atoms to achieve stability. Ion: an atom that has a positive or negative charge because it has unequal numbers of protons and electrons. If an atom gives up or gains and electron it becomes a charged ion (process = ionization: ex. Ca2: molecule: two or more atoms sharing electrons, ex.
