Why is the Periodic Table importantto me?• The periodic table is themost useful tool to achemist.• You get to use it onevery test.• It organizes lots ofinformation about all theknown elements.
Pre-Periodic Table Chemistry …• …was a mess!!!• No organization ofelements.• Imagine going to a grocerystore with no organization!!• Difficult to find information.• Chemistry didn’t makesense.
Dmitri Mendeleev: Father of theTableHOW HIS WORKED…• Put elements in rows byincreasing atomic weight.• Put elements in columnsby the way they reacted.SOME PROBLEMS…• He left blank spaces forwhat he said wereundiscovered elements.(Turned out he wasright!)• He broke the pattern ofincreasing atomic weightto keep similar reactingelements together.
The Current Periodic Table• Mendeleev wasn’t too far off.• Now the elements are put in rows by increasingATOMIC NUMBER!!• The horizontal rows are called periods and arelabeled from 1 to 7.• The vertical columns are called groups arelabeled from 1 to 18.
Groups…Here’s Where the PeriodicTable Gets Useful!!• Elements in thesame grouphave similarchemical andphysicalproperties!!• (Mendeleev did that on purpose.)Why??• They have the samenumber of valenceelectrons.• They will form the samekinds of ions.
Families on the Periodic Table• Columns are also groupedinto families.• Families may be one column,or several columns puttogether.• Families have names ratherthan numbers. (Just like yourfamily has a common lastname.)
Hydrogen• Hydrogen belongs to a familyof its own.• Hydrogen is a diatomic,reactive gas.• Hydrogen was involved in theexplosion of the Hindenberg.• Hydrogen is promising as analternative fuel source forautomobiles
Alkali Metals• 1stcolumn on the periodictable (Group 1) notincluding hydrogen.• Very reactive metals,always combined withsomething else in nature(like in salt).• Soft enough to cut with abutter knife
Alkaline Earth Metals• Second column on theperiodic table. (Group 2)• Reactive metals that arealways combined withnonmetals in nature.• Several of theseelements are importantmineral nutrients (suchas Mg and Ca
Transition Metals• Elements in groups 3-12• Less reactive hardermetals• Includes metals used injewelry and construction.• Metals used “as metal.”
Boron Family• Elements in group 13• Aluminum metal wasonce rare and expensive,not a “disposable metal.”
Carbon Family • Elements in group 14• Contains elementsimportant to life andcomputers.• Carbon is the basis foran entire branch ofchemistry.• Silicon and Germaniumare importantsemiconductors.
Nitrogen Family• Elements in group 15• Nitrogen makes up over¾ of the atmosphere.• Nitrogen and phosphorusare both important inliving things.• Most of the world’snitrogen is not availableto living things.• The red stuff on the tip ofmatches is phosphorus.
Oxygen Family or Chalcogens• Elements in group 16• Oxygen is necessary forrespiration.• Many things that stink,contain sulfur (rotteneggs, garlic, skunks,etc.)
Halogens• Elements in group 17• Very reactive, volatile,diatomic, nonmetals• Always found combinedwith other element innature .• Used as disinfectantsand to strengthen teeth.