Mendeleev did not know that some elements existedbut thought they did and left room for them.•The element hydrogen (H) is the lightest and mostabundant element in the Universe.•Atoms are electrically neutral! The cloud of negativecharges exactly balances the positive nucleus.
Metals• Hard, shinny, malleable, ductile, conductheat and electricity• Alkali Metals (IA) +1– Same traits of metals except soft– Most reactive metals-never found free innature– In pure form placed under oil so will not react
• Alkaline Earth Metals (IIA) +2– Very reactive– Not found pure in natureMagnesium: in chlorophyll, Epsom saltsCalcium: plaster, mortar, glass, Lime (CaO)Strontium: fireworksBarium: x-raysRadium: Cancer
Transition Elements• III B –II B• All metals• Sub groups – short Families• 1 to 2 electrons• High melting point and hard• Ions are colored
Non-metals• Are poor conductors of electricity and heat• Reactive with other elements• Solid non-metals are dull and brittle• Ten of the 16 are gases at roomtemperature.
Families of Non Metals• Carbon family IV A +/- 4• Nitrogen family V A -3• Oxygen family VI A -2• Halogen family VII A -1• Noble Gases VIII A 0
Metalloids• Have characteristics of both metals andnonmetals.• All are solids at room temperature.• They are brittle, hard and somewhatreactive.• The most useful property of the metalloidsis their varying ability to conduct electricity.