2The Periodic TableDmitri Mendeleev ( ) determined the properties of every known element at the timeAtomic MassDensityColourMelting PointBoiling Point
3The Periodic Table: Periods Mendeleev arranged the known elements in order of increasing atomic massHe found that the properties of the elements repeated at definite, or PERIODIC, intervalsNa has similar properties to Li and K
4The Modern Periodic Table: Atomic Number In 1915, the Periodic Table was reorganized based on the element’s atomic structureEach element has an ATOMIC NUMBER, which is unique to each elementThe atomic number begins with H (1) in the upper-left hand corner, and moves from Left to Right
5The Modern Periodic Table: Groups Vertical columns in the periodic tableChemical familiesElements in a group share very similar propertiesNumbered from 1-18Elements in the same GROUP have the same number of atomic SHELLS where VALENCE ELECTRONS (outer electrons) are held
6Elements are grouped based on specific properties: NonmetalsMetalloidsMetals
7Solid at Room Temperature Shiny Lustre MetalsShiny LustreGood Conductors (Heat/Electricity)Gas, Solid and Liquid at Room TemperatureNon-MetalsNot LustreousPoor ConductorsSolids at Room TemperatureMetalloidsShinyDullorPoor Heat ConductorMay Conduct Electricity
8The Modern Periodic Table: Characteristics of Groups The number of valence electrons in the elements is same in a group.The atomic radii increase from top to bottomMetallic Elements:Metallic character and chemical reactivity increase from top to bottomNon-Metallic Elements:Metallic character and chemical reactivity decrease from top to bottom
9Mg and Ca React with Hydrochloric Acid (Same Group) Elements are ordered in the periodic table according to reactivity and atomic number:F, Cl, I are gasesFClIMg and Ca React with Hydrochloric Acid (Same Group)MgCaNa and K react with WaterNaK
10The Modern Periodic Table: Groups of Elements 1182
11Group 1: Alkali MetalsVery reactive metals that do not occur freely in nature (Cs, Fr the most reactive)Valence Electrons: One; ready to lose that one electron to bond with other elements.Properties: Malleable, ductile, good conductors of heat and electricity, softer than most metalsCan explode if exposed to water.
12Group 2: Alkaline Earth Metals Very reactiveValence Electrons: 2; can bond easily with other elementsNot found free in nature
13Groups 3-12: Transition Metals Properties: Ductile, malleable, conduct electricity and heatValence Electrons: present in more than one shellIron, cobalt, and nickel are the only elements known to produce a magnetic field.
14Groups 13-15: Other MetalsProperties: Ductile and malleable, solid, high density, opaqueValence Electrons: present in their outer shell.
15MetalloidsAlong the stair-step line that distinguishes metals from non-metalsAl is an exception as it is classified as an “Other Metal”Properties: Similar to metals and non-metalsSi and Ge are semi-conductors (can carry an electrical charge under special conditions; used in calculators and computers)
16Group 14-16: Non-MetalsProperties: Do not conduct electricity or heat very well, brittle, not malleable or ductile, no luster, do not reflect lightExist as gases (N, O) or solids (C, S)
17Group 17: Halogens“Salt-former”, compounds containing halogens are called “salts”Valence Electrons: 7; will bond easily with Alkali Metals.Exist as solids (I, At), liquid (Br), and gas (F, Cl)
18Group 18: Noble GasesValence Electrons: 0; prevents gases from readily forming compoundsVery stable because they have the maximum electrons in their outer shell
19Rare Earth ElementsLanthanide and Actinide series (Group 3 and Period 6-7)One element of the lanthanide series and most of the elements in the actinide series are trans-uranium (synthetic or man-made)
20Mendeleev’s Periodic Law If the elements are arranged according to their atomic mass, a pattern can be seen in which similar properties occur regularly