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The Periodic Law

The Periodic Law. Chp 5 pg 122. I. The periodic Law. History of the Periodic Table Mendeleev Wanted to organize elements by properties Left empty spaces for elements that hadn’t been discovered Elements were discovered and fit in his spaces. Dmitri Mendeleev. 2. Moseley

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The Periodic Law

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  1. The Periodic Law Chp 5 pg 122

  2. I. The periodic Law • History of the Periodic Table • Mendeleev • Wanted to organize elements by properties • Left empty spaces for elements that hadn’t been discovered • Elements were discovered and fit in his spaces

  3. Dmitri Mendeleev

  4. 2. Moseley • Arranged elements by number of protons • Worked with what Mendeleev said

  5. 3. Modern Periodic Table a. Changed many times before what we have now b. Periodic table – arrangement of elements in order of their atomic #s so elements w/same properties are in the same column c. Noble gases 1) Took long time to discover 2) Don’t react

  6. d. Lanthanides – atomic numbers 58 – 71 e. Actinides – atomic numbers 90 – 103 f. Lanth and act, belong in periods 6 &7 in between families 3 and 4 1) Period – horizontal row 2) Family (groups) a) Columns b) Same number of val. electrons c) Causes same properties

  7. B. Electron Configuration & Per. table • Electrons of highest energy level give atom’s properties (valence electrons) • Periods and Blocks of Periodic Table • Period tells what energy level • Families determine # of valence electrons

  8. c. Blocks – tells which sublevel is filled 1) s-block = groups 1 and 2 2) p-block = groups 13-18 (not helium) 3) d-block = group 3-12 4) f-block = lanthanides, actinides

  9. 3. s-block elements a. Chemically reactive metals b. Family 1 = more reactive than 2 c. Alkali metals 1) Family 1 2) One valence electron 3) Lose electron easily 4) Silvery appearance 5) Very soft – cut with knife 6) Not found as free elements 7) More reactive at bottom of table

  10. d. Alkaline-earth metals 1) Group 2 2) 2 valence electrons 3) Harder, denser, and stronger than group 1 4) Higher melting points 5) Not free elements 6) Calcium: bones, limestone, marble MacGyver – Na bomb http://www.youtube.com/watch?v=Q0ASFXacVK0

  11. 4. Hydrogen and Helium a. Hydrogen 1) Doesn’t have same properties as family 1 2) Used in ammonia (NH3) and fertilizers b. Helium 1) Not reactive 2) Only 2 electrons

  12. Hindenburg Used H not He

  13. 5. d-block elements (Groups 3-12) a. Transition metals b. Good conductors – heat and electricity c. High luster d. Less reactive than families 1 & 2 e. Can exist as free elements Mercury: http://www.youtube.com/watch?v=gjR6ZJzXdIs&feature=relmfu

  14. 6. p-block elements a. Valence electrons = family number minus 10 b. Has metalloids and nonmetals c. Halogens 1) Most reactive nonmetals 2) Family 17 d. Metalloids (semiconductor) 1) Both sides of zigzag 2) Brittle solids 3) Characteristics of metals and nonmetals

  15. e. Noble gases 1) Group 18 2) Full outer shell (8 val. electrons) 3) Argon first discovered a) William Ramsey b) From Greek word argos meaning “lazy” or “inactive”

  16. 7. f-block elements a. Lanthanides 1) Shiny 2) Used in color TV and monitors b. Actinides 1) Radioactive 2) 94 – 103 are only in labs

  17. C. Alloys • Mixture of 2 or more elements of which at least one is a metal • Examples • Sterling silver • Silver and copper • Resists corrosion and stronger than silver

  18. b. Steel 1) Mix of iron, carbon, and sometimes manganese and nickel 2) Very strong c. Stainless steel 1) Steel and chromium 2) Resists rust

  19. Alloys Sterling silver Stainless steel

  20. C. Electron Configuration and periodic properties • Atomic Radii • ½ the distance between 2 nuclei of identical atoms bonded together

  21. b. Gets smaller going to the right 1) More electrons and protons 2) Pull things together more c. Get larger going down a group

  22. 2. Ionization Energy a. Electrons can be removed w/enough energy b. Ion – atom with a charge c. Ionization – anything that causes the formation of ions d. Ionization energy – energy needed to remove electrons e. Low IE = high reactivity f. 2nd electron takes more energy to remove than 1st; 3rd more than 2nd

  23. 3. Electron Affinity a. Energy change that occurs when an electron is added to a neutral atom b. Atom will be unstable and lose the electron c. Halogens gain them rapidly d. Decreases down a group e. Increases going left to right across period

  24. 4. Ionic Radii a. Cation – positive ion 1) Loss of 1 or more electrons 2) Decrease in atomic radius; smaller electron cloud 3) Typically metals b. Anion – negative ion 1) Adding 1 or more electrons 2) Increase in atomic radius 3) Typically nonmetals

  25. 5. Valence Electrons (150) a. Electrons that are gained, lost, or shared are valence electrons b. Outermost electrons c. Found in completely filled orbits d. Determining number of valence electrons 1) Group 1 & 2 – have 1 & 2 valence electron 2) Group 13-18 – subtract 10 from group #

  26. 6. Electronegativity a. How well an atom in a chemical compound attracts electrons b. Makes a higher concentration of electrons c. Decreases down a group d. Increases left to right across period

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