Presentation on theme: "The History and Arrangement of the Periodic Table"— Presentation transcript:
1 The History and Arrangement of the Periodic Table
2 History of the Periodic Table 1869 – Dmitri Mendeleev (Russian Chemist) thought elements may have something in common.Organized the elements into a tableMade each element a card and listed its properties known at the time (mass, density, color, melting point and valence number).
3 Dmitri Mendeleev (cont.) Mendeleev organized each card (element) according to its atomic mass (mass #)Noticed a repeating pattern of valence numbers (1,2,3,4,5 etc..)Noticed elements fell in to columns (groups)Noticed all elements in a column had the same valence number and showed similar physical and chemical properties.
4 Henry MoseleyMendeleev left blank spaces in his table so elements would line up – he also predicted what properties the undiscovered elements would have.1913 – Henry Moseley (English Scientist) changed the arrangement of the periodic table. Instead of by increasing atomic mass (mass #), it was arranged by increasing: atomic number (# of protons).
5 Arrangement of the Periodic Table Systematic arrangement of the elementsArranged by atomic number and propertiesNumbered groups / families are in vertical columnsPeriods are by amount of energy levels in horizontal rows (1-7)Divided into metals, nonmetals and metalloids
6 Metals - propertiesElements that begin at the left side of the periodic tableGood conductors of electricityShinyDuctile – can be drawn into thin wiresMalleable – can be hammered into thin sheets and other shapesHigh melting pointTend to loose electrons
7 Nonmetals - properties Elements that are to the right of the zigzag on the periodic tableNot shiny, dull in appearanceDo not conduct heat or electricityAre brittle and break easilyCannot be drawn into wire or hammered into sheetsLower densitiesLower melting pointsTend to gain electrons
8 Metalloids - properties Elements that are found along both sides of the zigzag lineSolidsCan be shiny or dull conduct heat and electricity better than nonmetals but not as well as metalsBoth ductile and malleable
9 Chemical Groups (Families) Elements that are in the same group or family (column) of the Periodic Table have similar properties because they have the same number of valence electrons
10 Group (Family) 1 - Alkali Metals 1 valence electron in outer energy levelVery reactive substances so it easily bonds with other substancesEasily loses 1 electron to form a stable +1 ion (ionic bond)Never found alone in natureSoft, silver-white, shiny
11 Group (Family) 2 - Alkaline Earth Metals 2 valence electrons in outer energy levelLoses 2 electrons to form +2 ionsSecond most reactive elements but not as reactive as group #1, so bonds easily with other substancesNever found alone in natureWill always bond ionically in natureFound combined with oxygen and other non-metals in the Earth’ crust
12 Groups 3-12 The Transition Metals 1 or 2 valence electronsCan lose and or share valence electronsCan have many multiple electrons in 2nd to last energy levelsCommon metals – gold, silver & copperThe U.S. imports at least 60 of these types of elements which are strategic and vital for our economy
13 From Metals to Nonmetals (outer energy level) Group 13 – Boron Group/Family 3 valence electrons- metalloids and metals in group- usually bonds covalentlyGroup 14 Carbon Group 4 valence electrons- non-metals, metals and metalloids- will always bond covalently ( electron sharing)- contain elements which are essential for cell functions
14 - will always bond covalently Group 15 Nitrogen Group 5 valence electrons- non-metals, metalloids and metals- will always bond covalentlyGroup 16 Oxygen Group 6 valence electrons- will bond covalently and ionically in natureGroup 17 Halogen Group 7 valence electrons- all non-metals that are very reactive and form compoundscalled halides ( salts)- bonds covalently and ionically
15 - colorless Group 18 Noble Gases 8 valence electrons - non-reactive ( inert ) / very stable- have a full outer shell filledwith electrons- non-metals
16 Rare Earth Elements (Inner Transition Metals) First Row – Lanthanide Series- naturally found rare Earth metals- all but one is non-radioactiveSecond Row – Actinide Series- most are man-made and radioactive- many are short-lived