3 I. History of the Periodic Table 1869 – Dmitri Mendeleev (Russian Chemist) thought elements may have something in common.Made each element a card and listed its properties known at the time (mass, density, color, melting point and valence number).Organized the elements into a table according to their atomic mass.
5 Dmitri Mendeleev – Columns = Groups/Families Noticed a repeating pattern of valence electrons (1,2,3,4,5 etc..)Noticed elements fell in tocolumns (groups or families)Noticed all elements in a column had the same valence electrons and showed similar physical and chemical properties.
6 Amazing Facts with his cards! Mendeleev left blank spaces in his table so elements would line up – he also predicted what properties the undiscovered elements would have.He predicted properties of five of these elements and their compounds. Three of these missing elements were discovered by others within 15 years.The element, atomic number 101, has been named after Mendeleev.
7 Mendeleev’s Periodic Table by atomic mass (with empty spaces for elements that would soon be discovered)
8 Henry Moseley1913 – Henry Moseley (English Scientist) changed the arrangement of the periodic table.Instead of by increasing atomic mass , Moseley arranged the elements by increasing: atomic number (# of protons).Interesting fact: Moseley's law = the energy of x-raysemitted from an element is related to its atomic number.
9 II. Arrangement of the Periodic Table Systematic arrangement of the elements by atomic number and chemical propertiesDivided into Regions:Metals, Nonmetals and MetalloidsVertical Columns – Numbered groups/familiesHorizontal Rows - Periods are by amount of energy levels (1-7) or orbital shells
11 Metals - location, properties Elements on the left side of the tableGood conductors of electricityShinyDuctile – can be drawn into thin wiresMalleable – can be hammered into thin sheets or shapesHigh melting pointTend to lose electrons
13 Nonmetals - location, properties Elements on the right of the zigzag on the tableDo not conduct electricity or heatDull in appearance, not shinyBrittle or break easilyNot Ductile or Malleable (cannot be drawn into wire or hammered into sheets)Lower densitiesLower melting pointsTend to gain electrons or share electrons with each other
15 Metalloids - location, properties Elements that are found along both sides of the zigzag line (except for Al)Properties of both metals and nonmetalsSemiconductors - conduct heat and electricity better than nonmetals but not as well as metalsSolidsCan be shiny or dullBoth ductile and malleable
17 IV. 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
18 Group (Family) 1 - Alkali Metals Very reactive , bonds easily with other substances (unstable and explosive)Never found alone in natureSoft, silver-white, shiny1 valence electron in outer energy levelEasily lose 1 electron to form a stable +1 ionForms ionic bonds
19 Think it Over:Hydrogen is a nonmetal gas, and forms covalent bonds. So why is it in the Alkali Metal family?
20 Group/Family 2 - Alkaline Earth Metals 2nd most reactive elements, bond easily with other substances, unstableNever found alone in nature2 valence electrons in outer energy levelLoses 2 electrons to form stable +2 ionsForms ionic bonds
21 Groups 3-12 The Transition Metals UnpredictableCommon metals – gold, silver & copperCan lose and/or share valence electronsForms Metallic Bonds
22 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 andmost are radioactive- many are short-lived
23 From Metals to Nonmetals Group #NameValence ElectronsBondsRegion13Boron Family3CovalentIonic(lose)Metalloids & Metals14Carbon FamilyBasis of Life4Metals, Metalloids Nonmetals
24 From Metals to Nonmetals Group #NameValence ElectronsBondsRegion15Nitrogen5CovalentIonic (Gains)Metals, Metalloids Nonmetals16Oxygen6Covalent orIonic (Gainselectrons)
25 From Metals to Nonmetals Group #NameValence ElectronsBondsRegion17Halogen7Covalent orIonic(Gains Electrons)NonmetalsVeryReactive18Noble Gases or Inert Gases8*Does not bondStableNon reactiveFull outer shells* Helium has a full outer shellwith 2 valence electrons
26 Stability Groups 1-17 are unstable The Noble Gas group/family is stableThink it Over: What makes an element stable?
27 Point to PonderThe element Carbon is the “Basis of Life”. What is meant by this?