Structure: Elements Elements: one type of atom Classification in the Periodic Table: Groups or Families: have similar characteristics Characteristics: Symbol: 2 letters: Capital and lower case Name: Atomic Number: # of protons Atomic Mass:# of protons + # of Neutrons Properties: metal, non-metal
Structure: Elements Electron Shells: 2, 8, 8, 18 electron spaces (for our purposes) Drawing an atom Valance shell electrons: The electrons in the outer most shell. Generally these electrons are involved in bonding.
Structure: Elements Isotopes: Have different versions of an element with different numbers of neutrons Atomic weight (revisited): Why a decimal number? Average weight of isotopes
Structure: Periodic Table Columns: Groups or Families • Have the same number of valance shell electrons • Families can be referred to by name or number Rows: periods Increasing Atomic number
Structure: Groups/ Families Hydrogen H: all by itself! METALS (generally solids) Alkali Metals (group 1): 1 valance electron, very reactive, never found alone Alkaline Earth Metals (group 2): 2 valance electrons, fairly reactive, never found alone Transition Metals (groups 3-12) : familiar metals, hard shiny, less reactive, versatile Metalloids: (stair step) both metal and non metal properties some conduct electricity some do not depending on temperature, used in semi -conductors in electronics
Structure: Groups/ Families NON-METALS (generally gases ) Carbon Group: 4 valance electrons- can gain or loose electrons to complete valance shell Nitrogen Group: 5 valance electrons, Oxygen Group: 6 valance electrons Halogen Group: 7 valance electrons, very reactive, salt forming, when alone very dangerous Noble gases: full valance shell, very stable
Structure: Groups/ Families RARE EARTH METALS/ SYNTHETIC This group fits into the transition metals. Lanthanides: rare metals, all very similar, soft malleable metals, used in alloys Actinides: rare metals, radioactive, most are synthetic (man-made in particle accelerators)