PartChargeLocation ProtonPositive (+)In the nucleus NeutronNeutral ( )In the nucleus ElectronsNegative (-)Orbiting around the nucleus

 He created the periodic table of elements in At this time there were 63 elements.  He noticed that a pattern of properties appeared when he arranged the elements in order of increasing atomic mass.

 The word periodic means “in a regular, repeated pattern.”  The table we read today is arranged according to increasing atomic number.  The properties of an element can be predicted from its location in the periodic table.

Each square on the periodic table includes:  Atomic number  Chemical Symbol  Chemical Name  Atomic mass

 Mass number - sum of the protons and neutrons in the nucleus.  Atomic mass - the average mass of all isotopes of an element.  Atomic number - the number of protons in the nucleus.  Isotopes - atoms with the same number of protons and a different number of neutrons. Example Carbon 12, 13, and 14.

 PERIODS  Horizontal  Numbered 1-7  Relate to weeks on a calendar  GROUPS (families)  Vertical  Numbered 1-18  Relate to same days on a calendar  Similar characteristics

 Luster - shininess  Malleable-hammered or pressed into flat sheets  Ductile-pulled out or drawn into a long wire  Conductive-ability to transfer heat or electricity  Color-produced when heated  Magnetic-attracted to a magnet or become magnetic Chemical Properties of Metals *Reactivity-ease and speed with which an element combines, or reacts with other elements and compounds *Corrosion-the destruction of a metal as it is exposed to other elements (rust)

 Group 1 (Alkali Metals) – most reactive group of metals, shiny and soft  Group 2 (Alkaline Earth Metals) – reactive, fairly hard and good conductors of electricity  Groups 3 – 12 (Transition Metals) – hard, shiny, good conductors of electricity  Group 17 – (Halogens) – highly reactive nonmetals, salt-forming  Group 18 – (Noble Gases) – unreactive, very stable

 Brittle - breaks apart easily  Dull  Poor Conductors  Most are gases  Reactive with other elements (Group 17)

 These are elements that have some characteristics of the metals and the nonmetals.  The most useful property of the metalloids is their varying ability to conduct electricity.  Semiconductors - substances that can conduct electricity under some conditions but not under other conditions  Ex. B, Si, Ge, As