Elements•  Simplestformofma0erthatismadeupofonetypeofatom.

•  Overa100differentelementshavebeendiscovered.

•  Webelievethereareonly118differentelementsthatcanexist.

•  Elementsareorganizedandgroupedonachartknownastheperiodictable.

PeriodicTableofElements• DmitriMendeleev• RussianChemist• 1834‐1907• Createdoneofthefirstperiodictables.• Placed63elementsonhistablebyusingtheelement’satomicmass.

Mendeleev’sPeriodicTable

HenryMoseley •  1887‐1915•  Englishphysicist

•  OrganizedtheelementssystemaScallybasedonthe#ofprotonsintheirnucleus.

•  Thustheelementsaregroupedbytheiratomic#today.

ModernPeriodicTable

ModernPeriodicTable

SymbolizingtheElements

Carbon Sodium

USlizingtheInformaSononthePeriodicTable

•  The#ofprotonsdeterminestheatomic#ofanatom.

•  Ontheperiodictablethe#ofprotonsisequaltothe#ofelectronsinanatom.Thereforeatomsontheperiodictablelackacharge.

•  #ofprotons+#ofneutrons=Atomicmass

Isotopes•  Atomsofthesameelementwithavarying#ofneutrons,andthusavaryingatomicmass.

•  Isotopeshavethesame#ofelectronsandprotons.

•  Isotopeshavethesameatomic#.

•  SomeisotopesareradioacSve.

IsotopesofCarbonCarbon‐12 Carbon‐14