Notes 11 14 08 To 11 21 08


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Notes 11 14 08 To 11 21 08

  1. 1. The Periodic Table Unit 3 Chapter 4 pp 114-131
  2. 2. Ok, so now what? <ul><li>Recall: Element cannot be broken down any further. </li></ul><ul><li>In the late 1800’s, we had “discovered” about 60 elements. </li></ul><ul><li>We had no idea of the structure of atoms. </li></ul><ul><li>Many scientists attempted to put order to the rapidly expanding list of elements. </li></ul>
  3. 3. Off to the Newlands… <ul><li>Arranged known elements in a table by atomic mass in 1863. </li></ul><ul><li>Noticed a repeating pattern every 8 th element in 1865. </li></ul><ul><li>Law of Octaves – chemical properties repeat every 8 elements. </li></ul><ul><li>Was laughed at by peers. </li></ul>John Newlands (1837-1898)
  4. 4. Newland’s Flaw <ul><li>Knew nothing of subatomic particles </li></ul><ul><li>His table mixed some obviously different elements (like oxygen and iron) </li></ul>
  5. 5. The Mad Russian <ul><li>Produced a more orderly table independent of Newlands’ work in 1869 (also used atomic mass). </li></ul><ul><li>Left blanks for yet-undiscovered elements. </li></ul><ul><li>Predicted properties of Ga, Sc, and Ge (disc. 1875, 1877, & 1886). </li></ul><ul><li>Credited with the Periodic Table. </li></ul>Dmitri Mendeleev (1834-1907)
  6. 6. Russian Roulette <ul><li>Mendeleev’s table had a few problems. </li></ul><ul><li>Based on atomic mass, had to switch a few elements (e.g. Tellurium and Iodine) to keep reactivities in order. </li></ul><ul><li>Many believed he predicted too many elements (we had 63 already!!!). </li></ul><ul><li>Still, this is what we used for half a century. </li></ul>
  7. 7. 45 Years Later… <ul><li>Rearranged table according to electronic charge in 1914. </li></ul><ul><ul><li>Became the # of protons after 1918. </li></ul></ul><ul><li>Noticed his new table had spots for #’s 43, 61, 72, & 75. </li></ul><ul><li>Produced the modern periodic table we know today. </li></ul><ul><li>Enlisted in the army’s Royal Engineers when WWI broke out. </li></ul>Henry Moseley (1887 – 1915)
  8. 8. Moseley’s New Order <ul><li>Gave experimental meaning to atomic number. </li></ul><ul><li>Gave reason for Tellurium and Iodine being switched. </li></ul><ul><li>Moseley’s technique easily separated rare earth metals. </li></ul><ul><ul><li>Plagued chemists for years and years. </li></ul></ul><ul><li>Predicted how many elements remained between others. </li></ul><ul><li>(e.g. 13 elements between La and Lu) </li></ul>
  9. 9. Moseley’s Lost Nobel <ul><li>Many thought he should have won Nobel Prize. </li></ul><ul><li>It’s only given to the living…he was shot in the head by a sniper in Gallipoli. </li></ul><ul><li>Bohr (1962): &quot;You see actually the Rutherford work [the nuclear atom] was not taken seriously. We cannot understand today, but it was not taken seriously at all. There was no mention of it any place. The great change came from Moseley.&quot; </li></ul><ul><li>British barred scientists from enlisting for combat. </li></ul>
  10. 10. Elements Everywhere <ul><li>Based on increasing number of protons, we now have a complete periodic table. </li></ul><ul><li>Will not find any lower elements, can only go up (118 so far). </li></ul><ul><li>Create new elements by smashing smaller atoms together: </li></ul>3 Neutrons 294 118 Uuo 48 20 Ca 249 98 Cf
  11. 11. Periodicity <ul><li>In order by atomic number (# of Protons) </li></ul><ul><ul><li>H has 1 p + , U has 92 </li></ul></ul><ul><li>Arranged in Rows and Columns </li></ul><ul><li>Rows = Periods </li></ul><ul><ul><li>Pd 3 = Na, Mg, Al, Si, P, S, Cl, Ar </li></ul></ul><ul><li>Columns = Groups or Families </li></ul><ul><ul><li>Group 1 = H, Li, Na, K, Rb, Cs, Fr </li></ul></ul><ul><ul><li>Have similar properties </li></ul></ul><ul><ul><li>(e.g. Form hydroxides: LiOH, NaOH, KOH, etc) </li></ul></ul>
  12. 12. Division of Labor <ul><li>Different types of elements are found on different parts of the table: </li></ul><ul><ul><li>Metals to the left (majority of the elements). </li></ul></ul><ul><ul><li>Nonmetals to the right (18 elements). </li></ul></ul><ul><ul><li>Metalloids found on a “staircase” dividing metals and nonmetals (7 elements). </li></ul></ul><ul><ul><li>Lanthanoids & Actinoids (metals) added to bottom to make table manageable. </li></ul></ul>
  13. 13. Metals <ul><li>Lustrous (shiny) </li></ul><ul><li>Malleable (can be pounded into thin sheets) </li></ul><ul><li>Ductile (can be pulled into wires) </li></ul><ul><li>Conductive </li></ul><ul><ul><li>Heat and electricity </li></ul></ul><ul><li>Form solid oxides when burned. </li></ul><ul><li>Tend to react with acids to form Hydrogen gas. </li></ul>
  14. 14. Nonmetals <ul><li>Wide range of properties </li></ul><ul><li>Tend to: </li></ul><ul><ul><li>Be Dull </li></ul></ul><ul><ul><li>Be Brittle (when solid) </li></ul></ul><ul><ul><li>Be Insulators </li></ul></ul><ul><ul><li>Form gaseous oxides </li></ul></ul><ul><ul><li>Not react with acids </li></ul></ul><ul><ul><li>Have lower melting & boiling points. </li></ul></ul>Bromine
  15. 15. Metalloids <ul><li>Also called “semi-metals” or “staircase elements.” </li></ul><ul><li>Combination of properties of metals and nonmetals. </li></ul><ul><li>Boron, Silicon, Germanium, Arsenic, Antimony, Tellurium, & Polonium </li></ul><ul><li>Many exhibit semi-conducting behavior. </li></ul>
  16. 16. Groups/Families <ul><li>Alkali Metals </li></ul><ul><li>Alkali Earth Metals </li></ul><ul><li>Halogens </li></ul><ul><li>Noble Gases </li></ul><ul><li>Transition Metals </li></ul><ul><li>Inner Transition Metals </li></ul><ul><ul><li>Lanthanoids (Rare Earths) </li></ul></ul><ul><ul><li>Actinoids </li></ul></ul>
  17. 17. s-Block Elements <ul><li>At least 1 e - in s orbital (ns x ) </li></ul><ul><li>Groups 1 & 2 </li></ul><ul><ul><li>Alkali Metals </li></ul></ul><ul><ul><li>Alkaline Earth Metals </li></ul></ul><ul><li>Reactivity increases as you go down </li></ul><ul><li>All are metals, except H & He </li></ul><ul><li>Helium is technically an s-block, but placed with Noble Gases b/c of reactivity </li></ul>
  18. 18. p-Block Elements <ul><li>At least 1 e - in p orbital (np x ) </li></ul><ul><li>Groups 13-18 </li></ul><ul><li>Nonmetals at top, gradually transitioning into metals </li></ul><ul><li>All nonmetals and metalloids are p-block elements (excl H & He) </li></ul><ul><li>Some metals (Al, Ga, In, Sn, Tl, Pb, Bi) </li></ul>
  19. 19. d-Block Elements <ul><li>At least 1 e - in d orbital (nd x ) </li></ul><ul><li>Groups 3-12 </li></ul><ul><ul><li>Transition Metals </li></ul></ul><ul><li>Very little similarities w/in group </li></ul><ul><li>All are metals </li></ul><ul><li>Most form multiple ions (charged atoms) </li></ul>
  20. 20. f-Block Elements <ul><li>At least 1 e - in f orbital (nf x ) </li></ul><ul><li>Oddballs </li></ul><ul><ul><li>Lanthanoids start with #57, La </li></ul></ul><ul><ul><li>Actinoids start with #89, Ac </li></ul></ul><ul><li>The groups are NOT similar up & down </li></ul><ul><li>All are metals </li></ul><ul><li>Lanthanoids (4f) are natural, most Actinoids (5f) are man-made </li></ul>
  21. 21. Representative Elements <ul><li>Exhibit nearly perfect periodicity. </li></ul><ul><ul><li>All members of these groups behave as expected. </li></ul></ul><ul><li>Groups on the outside of the table: </li></ul><ul><ul><li>Alkali Metals (Group 1) </li></ul></ul><ul><ul><li>Alkaline Earth Metals (Group 2) </li></ul></ul><ul><ul><li>Halogens (Group 17) </li></ul></ul><ul><ul><li>Noble Gases (Group 18) </li></ul></ul>
  22. 22. Alkali Metals <ul><li>Group 1 (excluding hydrogen) [ns 1 ] </li></ul><ul><li>Soft, lustrous, oxidize when exposed to air. </li></ul><ul><li>Difficult to isolate – never found in nature. </li></ul><ul><li>React (violently) with water to form a base. </li></ul><ul><li>React with chlorine to form a salt with a 1-to-1 ratio: </li></ul><ul><ul><li>LiCl </li></ul></ul><ul><ul><li>NaCl </li></ul></ul><ul><ul><li>KCl </li></ul></ul><ul><ul><li>RbCl </li></ul></ul><ul><ul><li>CsCl (also FrCl) </li></ul></ul>
  23. 23. Alkaline Earth Metals <ul><li>Group 2 [ns 2 ] </li></ul><ul><li>Harder & Denser than Alkali Metals. </li></ul><ul><li>Lustrous, oxidize slowly when exposed to air. </li></ul><ul><li>React with water or steam to form a base. </li></ul><ul><li>React with chlorine to form a salt with a 1-to-2 ratio: </li></ul><ul><ul><li>BeCl 2 </li></ul></ul><ul><ul><li>MgCl 2 </li></ul></ul><ul><ul><li>CaCl 2 </li></ul></ul><ul><ul><li>SrCl 2 </li></ul></ul><ul><ul><li>BaCl 2 </li></ul></ul><ul><ul><li>RaCl 2 </li></ul></ul>
  24. 24. Halogens <ul><li>Group 17 [np 5 ] </li></ul><ul><li>Nonmetals </li></ul><ul><li>Gases (F, Cl), liquid (Br), and solids (I, At) </li></ul><ul><li>Name means “salt former.” </li></ul><ul><li>React with sodium to form a salt with a 1-to-1 ratio: </li></ul><ul><ul><li>NaF </li></ul></ul><ul><ul><li>NaCl </li></ul></ul><ul><ul><li>NaBr </li></ul></ul><ul><ul><li>NaI </li></ul></ul><ul><ul><li>NaAt </li></ul></ul>
  25. 25. Noble Gases <ul><li>Group 18 [np 6 ] </li></ul><ul><li>Unreactive Gases – colorless, odorless. </li></ul><ul><li>Some of the last natural elements to be discovered. </li></ul><ul><li>Once called “Inert Gases.” </li></ul><ul><li>Monatomic in Nature </li></ul>
  26. 26. Non-representatives <ul><li>Other families have similarities, but do not behave exactly as expected </li></ul><ul><ul><li>Groups 13-16, start with Boron – Oxygen </li></ul></ul><ul><ul><li>More differences than similarities </li></ul></ul><ul><li>Others are lumped together for other reasons </li></ul><ul><ul><li>Transition Metals </li></ul></ul><ul><ul><li>Lanthanoids </li></ul></ul><ul><ul><li>Actinoids </li></ul></ul>
  27. 27. Transition Metals <ul><li>Groups 3 to 12 [nd x ] </li></ul><ul><li>Central portion of the PT. </li></ul><ul><li>Behavior and appearance vary. </li></ul><ul><li>Variable oxidation state (charge). </li></ul><ul><li>Different oxidation states can produce different colors. </li></ul><ul><li>Often used to make pigments. </li></ul>Co +2 Cr +6 Cr +6 Ni +2 Cu +2 Mn +7
  28. 28. Lanthanoids <ul><li>1 st Row on Bottom of table [4f x ] </li></ul><ul><li>AKA Lanthanides & Rare Earths </li></ul><ul><li>Not so rare (Ce 25 th most abundant) </li></ul><ul><li>So similar, very difficult to separate – remember Moseley? </li></ul><ul><li>Most deflect UV – used in sunglasses </li></ul><ul><li>Shiny, silvery white, soft, react violently with most nonmetals, tarnish in air </li></ul>
  29. 29. Actinoids <ul><li>2 nd Row on Bottom of table [5f x ] </li></ul><ul><li>AKA Actinides </li></ul><ul><li>All are radioactive </li></ul><ul><li>Not as similar as the Lanthanoids </li></ul><ul><li>Only Th and U are common in nature </li></ul><ul><li>Most are man-made </li></ul><ul><ul><li>Nuclear fallout </li></ul></ul><ul><ul><li>Particle colliders </li></ul></ul>
  30. 30. State of the Union <ul><li>Reacted State: </li></ul><ul><ul><li>When elements are combined with other elements to form compounds </li></ul></ul><ul><ul><li>Most common state </li></ul></ul><ul><li>Elemental State: </li></ul><ul><ul><li>When elements are uncombined </li></ul></ul><ul><ul><li>Most elements are Monatomic (one atom) </li></ul></ul><ul><ul><li>Some are always Diatomic (two atoms) </li></ul></ul><ul><ul><li>A few are Polyatomic (>2 atoms) </li></ul></ul>
  31. 31. Diatomics <ul><li>7 elements always form diatomic molecules when they are isolated in their elemental state…ALWAYS! </li></ul><ul><li>Hydrogen, Nitrogen, Oxygen, Fluorine, Chlorine, Bromine, & Iodine </li></ul><ul><li>These, you gotta memorize! </li></ul><ul><li>Luckily, Mr. Brinclhof is here to help! </li></ul>Br 2 I 2 N 2 Cl 2 H 2 O 2 F 2
  32. 32. Another Way <ul><li>The rule of “7” </li></ul><ul><li>Diatomics form a “7” on the Periodic Table excluding H </li></ul>2 2 2 2 2 2 2 I Te Sb Sn Br Se As Ge Cl S P Si F O N C H
  33. 33. The Oddballs <ul><li>Sulfur is normally found as S 8 </li></ul><ul><li>Selenium also forms Se 8 </li></ul><ul><li>Phosphorus forms P 4 </li></ul>
  34. 34. Allotrope <ul><li>When an element can be found in more than one form </li></ul><ul><li>Several elements have different allotropes, but most often cited is Carbon </li></ul><ul><li>Carbon has 3 common allotropes </li></ul><ul><ul><li>Amorphous – Random arrangement of C atoms </li></ul></ul><ul><ul><li>Graphite – Hexagonal arrangement in sheets </li></ul></ul><ul><ul><ul><li>Conducts electricity! </li></ul></ul></ul><ul><ul><li>Diamond – 3-D network solid </li></ul></ul>
  35. 35. Allotropes of C Amorphous C Diamond (Network Solid) Graphite (Sheets)
  36. 36. Trends in the Periodic Table <ul><li>Several trends appear once we have the elements in order </li></ul><ul><ul><li>Atomic Radius </li></ul></ul><ul><ul><li>Ionization Energy </li></ul></ul><ul><ul><li>Electronegativity </li></ul></ul><ul><ul><li>Reactivity </li></ul></ul>
  37. 37. Ray “D” Eye <ul><li>Atomic Radii DECREASE from left to right </li></ul><ul><li>They INCREASE from top to bottom </li></ul>Na is bigger than Ar (223 pm) (88 pm) I is bigger than F (132 pm) (57 pm) Na Mg Al Si P S Cl Ar I Br Cl F
  38. 38. Fluorine says, “Mine!” <ul><li>Electronegativity is a measure of how badly an element wants to gain an electron </li></ul><ul><li>It INCREASES from left to right </li></ul><ul><li>It DECREASES from top to bottom </li></ul>Ne -- F 3.98 O 3.44 N 3.04 C 2.55 B 2.04 Be 1.57 Li 0.98 I 2.66 Br 2.96 Cl 3.16
  39. 39. F has Codependency Issues <ul><li>Ionization Energy is the amount of energy required to remove an electron. </li></ul><ul><ul><li>It INCREASES from left to right </li></ul></ul><ul><ul><li>It DECREASES from top to bottom </li></ul></ul>Na needs less NRG than Cl (496 kj/mol) (1256 kj/mol) F needs more NRG than I (1681 kj/mol) (1008 kj/mol)
  40. 40. Major Trends in a Nutshell Atomic Radius Decreases Electronegativity Increases Ionization Energy Increases Fr F We usually ignore the Noble Gases
  41. 41. Reactivity <ul><li>Most reactive Metals are farther down and to the left </li></ul><ul><li>Most reactive Nonmetals are higher and to the right </li></ul>
  42. 42. Tidbits <ul><li>Hydrogen by far most abundant (4 out of every 5 atoms in universe) </li></ul><ul><li>Atoms in the Elemental state tend to be more dangerous/poisonous than those in the Reacted state – Exceptions: Cu & Pb </li></ul><ul><li>Oddo-Harkins Rule: even #’d elements more common than odd ones (protons apparently like to be paired up). </li></ul>