Atoms

Atoms

1. Structures

   • Proton
     • positive charge
     • large mass (dense)
   • Neutron
     • No charge
     • large mass (dense)
   • Electron
     • negative charge
     • smallest
     • electron shells
       • same last number = similar chemical properties
       • 2, 8, 8, 2

2. Elements

   • Mass number
     • top number
     • number of protons
   • Atomic number
     • bottom number
       • mass number = neutron + proton
   • Periodic table
     • Groups
       • Halogen (7)
         • Fluorine (9) [F]
         • Chlorine (17) [Cl]
       • Alkali (1)
         • Hydrogen (1) [H]
         • Lithium (3) [Li]
         • Sodium (11) [Na]
         • Potassium (19) [K]
       • Noble (8)
         • Helium (2) [He]
         • Neon (10) [Ne]
         • Argon (18) [Ar]
       • Alkaline earth (2)
         • Beryllium (4) [Be]
         • Magnesium (12) [Mg]
         • Calcium (20) [Ca]