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The Periodic Table of elements Elements in Earth’s Crust What are people made of? Classic Greek Mendeleev- First Periodic Table ( 1869) • Grouped by atomic mass & chemical properties. • Blank spaces were left to add predicted elements Mendeleev’s Periodic Table Mosley 1914- Modern P.T. • Atomic # • Similar property elements ended up next to each other •Periodic Law Periodic Law Repetition of physical & chemical properties due ↑ atomic # Modern Periodic Table Elements are arranged: Vertically into Groups Horizontally Into Periods Why? If you looked at an atom of each element in a group, you would see… Same # valence electrons. All atoms in group 2 have 2 electrons in their outer shells Be (Beryllium) Atom Mg (Magnesium) Atom If you looked at an atom from each element in a period you would see… All atoms in Period 4 have 4 Energy Levels 4th Shell K (Potassium) Kr (Krypton) Atom Atom Fe (Iron) Atom Shells = Ring= Orbit = E Level Periodic Patterns Element’s chemical behavior is determined by: its e- config Each Group has distinct properties Alkali Metals • 1 valence e-: ns1 • Most reactive metals • Always bonded with another element. Alkaline Earth Metals • 2 valence e-: ns2 • Never found free in nature • Found in rocks/ earth’s crust How many things can you think of that have Transition Metals in them? Hydrogen • In a class of its own • Gas @ room temp. Group 13: 3 valence eGroup 14: 4 valence eGroup 15: 5 valence eGroup 16: 6 valence e- ns2np1 ns2np2 ns2np3 ns2np4 Interesting facts • Carbon element of life • Nitrogen 78% atmosphere • Oxygen the most abundant element in earth’s crust Halogen • • • • 7 valence electrons ns2 np5 Most active non-metals. Never found free in nature Poisonous Noble Gases • • • • • Very stable 8 valence electrons ns2np6 Colorless gases Un reactive (inert) World’s running out of He Properties of Metals 1. Conductors of heat and electricity 2. Luster: shiny. 3. Ductile: stretched into thin wires 4. Malleable: pounded into thin sheets Properties of Metalloids • Metalloids :metal-like • Can be shiny or dull • Conduct heat/electricity better than non-metals but not as well as metals. • They are ductile and malleable. What are metalloids used for? Properties of Non-Metals • Not: ductile, malleable, shiny, or conductor • Brittle and break easily ELEMENT SONG Element Game
