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The Elements

The Elements. Chapter 7. Section 7.1 Prop of s-block. Objectives : Explain how elements in a given group are both similar and different Discuss the properties of H Describe and compare the properties of alkali and alkaline earth metals. General Info. 92 naturally occurring elements

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The Elements

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  1. The Elements Chapter 7

  2. Section 7.1 Prop of s-block • Objectives: • Explain how elements in a given group are both similar and different • Discuss the properties of H • Describe and compare the properties of alkali and alkaline earth metals

  3. General Info • 92 naturally occurring elements • He is the 2nd most common element in universe, and is much less on Earth • O most abundant on Earth • Atomic # > 92 do not exist in nature • They’re synthetic • Created in labs or nuclear reactors

  4. Representative elements • 1A  8A • s and p orbital • Diagonal relationships • Have common characteristics with elements diagonal to them

  5. Hydrogen • 1A because 1 valence e- • 7A characteristics • Contains metallic and nonmetallic properties • Not considered part of any group

  6. Hydrogen history • 1766 Henry Cavendish discovered H • “Flammable air” b/c burned when ignited in air • 1783 Lavoisier named H • Greek “hydro”-water, “genes” - to form Picture source Wikipedia.com

  7. Hydrogen Isotopes • Protium • 99.985% • No neutrons • Deuterium • 0.015% • 1 neutron • Tritium • 2 neutrons • Radioactive • Produced when cosmic rays bombard water in atmosphere • “heavy water” Picture source Wikipedia.com

  8. Hydrogen bonding • Gain e- • H + H  stable configuration of He • Lose e- • H+ ion with no e-

  9. Group 1A: Alkali metals • Li • Na • K • Rb • Cs • Fr

  10. Alkali Metals • Arabic “al-qili” • “Ashes of saltwort plant” • Easily lose valence e-  1+ charge ion • Soft like cold butter • Highly reactive • Lab samples stored in oil to prevent O reaction • Good conductor of heat/electricity

  11. Lithium (Li) • Lightest alkali metal • Found in water, soil and rocks • Least reactive of alkali metals • Li & Mg diagonal relationship • Used in • batteries – extend life electric cars • Dehumidifiers – absorbs water • Li carbonate – strengthens glass, drug bipolar disorder • Alloys – plane parts b/c strong & lightweight Picture source http://www.webelements.com/webelements/elements/text/Li/key.html

  12. Na & K • Most abundant • Na vapor lamps • Heat exchanger in nuclear reactors • Humans and vertebrates need in diets • K+ most common in cells • Na+ most common in fluid outside cells • When nerve cell stimulated • K+ moves outside the cell when Na+ moves into the cell Picture source Wikipedia.com

  13. More Na and K info • NaCl most common Na compound • Prevent spoiling • Preserve food • KCl – salt substitute • K compound found in fertilizers for plant growth and development • KNO3 – explosives for fireworks Picture source http://www.webelements.com/webelements/elements/text/Na/key.html

  14. Other Alkali metals • Rb • extremely reactive • 40°C mp • Burst into flames when exposed to air • Fr • Most reactive • Rare radioactive element

  15. Group 2A: Alkaline Earth metals • Be • Mg • Ca • Sr • Ba • Ra All Picture sources from http://www.webelements.com/webelements/elements/text/Ra/key.html

  16. Alkaline Earth Metals • Medieval alchemist classified solids that did not melt in their fires as “earths” • AEM + O2 oxides  form thin oxide coating • Shiny solids • Harder than AM • Less reactive than AM • Found combined w/ O and other nonmetals • Lose 2 valence e-  2+ charge • Ca, Sr, Ba react with water • Be no react with water

  17. Beryllium (Be) • Lightest in Group 2A • Beryl is Be + Al + Si + O • Al & Be have diagonal relationship • Used to moderate n0 in nuclear reactors • Be-Cu tools used in petroleum refineries Picture source from http://www.webelements.com/webelements/elements/text/Be/key.html

  18. Calcium (Ca) • Essential for humans • Maintain teeth and bones • Calcium carbonate • Limestone, chalk, marble • Coral reefs • Antacid tablets • Toothpaste abrasives • Emery boards and sand paper • Limestone used to build Roman aqueduct • Calcium carbonate decomposes into lime Picture source from http://www.webelements.com/webelements/elements/text/Ca/key.html

  19. Lime • One of the most important industrial compounds • Manufacturing steel, paper and glass • Make soil more acidic • Wastewater treatment plants • Remove pollutants from smokestacks • Lime + water + sand = mortar (paste)

  20. Magnesium (Mg) • Alloys (Mg + Al + Zn) as strong as steel but lighter • Plants chlorophyll molecules contain Mg 2+ • Humans muscle function and metabolism • Hard water is increase in Ca 2+ and Mg 2+ • Interfere with detergent/ soap action • Clog pipes, water heaters, and steam irons

  21. Other AEM • Sr  • fireworks red color • Ba  • used in paints and glass • diagnostic tool for internal medicine • Ra  • highly radioactive • emit α, β, and γ • Painted hands on watches b/c glows at night

  22. Section 7.2 Prop of p-block • Objectives: • Describe and compare properties of p-block elements • Define allotropes and provide examples • Explain the importance to organisms of selected p-block elements

  23. Group 3A: Boron Group • B – metalloid • Al – abundant metal • Ga – rare metal • In – rare metal • Tl – rare metal

  24. More Boron Info • Lose 3 e-  3+ charge • Tl  1+ charge • Lose p e- only • Very metallic like AM • Ga and In can form 1+ also

  25. Boron (B) • Chemical properties like Si • Borosilicate glass • Withstand extreme temp changes w/o shattering • Borax • Large amount comes from CA Mojave Desert • Cleaning agent • Fireproof insulation • Boric Acid • Disinfectant in eye wash • Boron Nitride • Second hardest material • Super abrasive • Used in grinding wheels

  26. Aluminum (Al) • Most abundant metal • 3rd most abundant element of Earth’s crust • Combined w/ O or Si • Bauxite requires LOTS of energy • Al2O3 major compound in bauxite • Abrasive • Strengthens ceramics • Heat-resistant fabrics • Ruby and sapphires are crystals of Al2O3 • Cr  red • Fe + Ti  blue • Alum (Al sulfate) • Antiperspirants • Remove suspended particles during water purification

  27. Gallium (Ga) • Melts in your hand • Used in some thermometers b/c liquid state in large range (30 – 2403 °C) • Gallium arsenide (Ga + As)  produce electric current when absorbs light • Used in semiconductor chips • Light-powered calculators • Solar panels • 10x more efficient than Si based • Gallium nitride (Ga + N) • Blue lasers • Triple DVD storage capacity (3-2 hr movies per DVD) • Increase speed and resolution of laser printers • Lower cancer cell detection device cost

  28. Group 4A: Carbon Group • C – nonmetal • Si – metalloid • Ge – metalloid • Sn – metal • Pb – metal

  29. Carbon (C) • Organic chemistry – study of C-based compounds • 1828 – 1st C compound synthesized • Prior believed only living organisms made C based compounds • Minerals- element or inorganic compound found in natural as solid crystal • Ore- material form which a mineral can be removed at a reasonable cost • Cost to extract not > economic value

  30. C Allotropes • Allotropes – forms of element in same physical state (SLG) that have different structure and properties • Graphite • Softest known material • Good lubricant b/c molecules slide • 3 C attached • Diamond • Hardest known material • 4 C attached • 3D solid • Can cut granite and concrete • Coal • Shapeless solid

  31. Silicon (Si) • Second most abundant element on Earth’s crust after O • Used in • Computer chips • Solar cells • Silicon dioxide (SiO2) AKA: silica Quartz + weathering  white sand + heat and rapid cooling  glass • Si + C silicon carbide • Major industrial abrasive • Carborundum – common name • Used sticks to sharpen tools

  32. Pb & Sn • Sn  Coat steel cans; now use Al cans • Bronze alloy Sn + Cu, Zn (little for hardness) • Pewter  40% Pb & 60% Sn • Softer metal • Pb  ancient skeletal analysis  dangerously high levels • Toxic • Used in eating utensils • Pipes for plumbing • Gasoline additives • Paint • Car storage batteries (Pb-acid) p. 675-676

  33. Group 5A: Nitrogen Group • N – nonmetal • P – nonmetal • As – metalloid • Sb – metalloid • Bi – metal

  34. Nitrogen group info • 5 valence e- • Forms 3+/- charge ions

  35. Nitrogen • Colorless, odorless, relatively unreactive • 78% Earth’s atmosphere • Proteins and essential organic compounds • Bacteria and clover roots “fix” N • Major industrial use • Ammonia • Colorless gas with irritating odor • Cleaning products • N source for plants • 25% ammonia  nitric acid • Produced for explosives • Dyes • Fertilizers • Etching design on metal plates • TNT (trinitrotoluene) • nitroglycerine

  36. Phosphorus (P) • Allotropes • White P – bursts into flames in air • Must be stored in water • Red P – less reactive • Formed from white P heated in absence of air • Used on matchboxes for striking surface • Black P – white or red heated under high pressure • Phosphoric acid  phosphate compound • Used in processed cheese, laxatives, baking powder • Flame retardant coating on fabrics • Grease remover in cleaning products • Fertilizers have phosphates • Harmful to environment • Normal: phosphates broken down by bacteria  nutrients eaten by algae  zooplankton eat algae  fish eat zooplankton • Increase P ions: increase algae pop  keep light from algae below (die)  bacteria decay algae use lots of O  other things die  no decay and build up of waste occurs  lake changes to pond or marsh

  37. As, Sb, Bi • Oldest known elements • As + S  arsenic sulfide  treat illnesses; As toxic • Sb + S  antimony sulfide  cosmetics to darken eyebrows and make eyes appear larger • Britannia metal – alloy of Sn + Sb; easily shaped • Pb storage batteries – contain 7% Sb • Bi active ingredient in Pepto – diarrhea and nausea med • Wood’s metal – alloy of Bi, Pb, Sn, Cd • Plug automatic sprinkler; melts when heated and activates sprinkler (water)

  38. Group 6A: Oxygen Group • O – nonmetal • S – nonmetal • Se – metalloid • Te – metalloid • Po – rare metal

  39. Oxygen Group Info • 6 valence e- • Nonmetals mainly • Gain 2 e- • Forms 2 – charge • Shares 2 e- for stability when bonded

  40. Oxygen (O) Allotropes • Ozone (O3) • Unstable gas with pungent odor • Decomposes when exposed to UV light or heat • Produced in auto emissions • Irritates eyes, harmful to lung cells, and affects plant growth negatively • O2 • 21% Earth’s atmosphere • Colorless, odorless gas • Joseph Priestley (1733-1804) discovered O2 • Heated Hg oxide and candle burned more brightly than in air • Cellular respiration uses O2 to release energy from carbs • Separate from other gases by distillation • Canisters store liquid O2 • Airplanes have small, individual O2 for emergencies • Most abundant element in Earth’s crust • Combines with every element except He, Ne, Ar • H2O • H2O2 • CO • CO2

  41. Sulfur (S) • Combined w/ Hg (cinnabar) • Combined w/ Pb (galena) • Uncombined underground • 10 allotropes • SO2 • Preserve fruit • Antibacterial agent • Acid rain • 90% make sulfuric acid • Fertilizers (50%) • Steel, paper and paint • H sulfide • Rotten egg smell • Ocean vents energy source for bacteria • Volcanoes • Silver sulfide  tarnish

  42. Selenium (Se) • Na selenate – vitamin supplement contain this • Vitamin E prevent cell damage • Inhibit cancer cell growth • Locoweed plant – absorbs too much  toxic • Animals become ill • Light  electricity (solar panels) • Meters to measure light availability (photography) • Charge Se particles create image (photocopiers) • Semiconductors (& Te)

  43. Polonium (Po) • 1898 founded by Marie Curie • Named after Marie’s home country – Poland • Extremely toxic • Radioactive • Rare metal

  44. Group 7A: Halogens • F – gas • Cl – gas • Br – liquid • I – solid  gas • At – radioactive with no known uses

  45. Halogen Info • “salt formers” • Reactive nonmetal • Always found combined with other elements in nature • 7 valence e- • Share 1 e- or gain 1 e- • Forms 1- charge ion

  46. Fluorine (F) • Most electronegative element on PT • Greatest ability to attract e- • Most active of all elements • Reacts w/ every element except He, Ne, Ar • Latin “fluere” – to flow • Fluorite – F + Ca • Lower mp of other minerals, easier to separate from ore • F added to toothpaste and water to prevent tooth decay • F + C – non-stick cooking surfaces • F + U isotopes  gases separate by differences in mass (U enrichment)  provides U-235 fuel for nuclear reactors

  47. Chlorine (Cl) • Deadly gas • Reacts w/ nearly all elements • 1848 cholera epidemic began in London • 25,000 died • Culprit: raw sewage flowing into Thames R. • 1855 London 1st city to use Cl to disinfect sewage • Bleaching agents by textile and paper industry • Remove stains from clothes • Cl compound blocks pain signals during dental work • HCl in stomach digests food • Remove rust from steel (pickling) • Cl gas • Produced from oil refineries • Plastics  PVC (polyvinyl chloride) • Floor tiles • Pipes for indoor plumbing • Garden hoses

  48. Bromine & Iodine • Ag + Br and Ag + I • Coat photographic film • I  body  maintain thyroid gland • Control growth and metabolic rate • Goiter  enlarged thyroid gland • Lack of I • Seafood excellent source of I • Iodized salt (KI, NaI, and NaCl) • Kills bacteria • Campers  tablets/crystals to disinfect water

  49. Group 8A: Noble Gases • He • Ne • Ar • Kr • Xe • Rn

  50. Noble Gas Info • Colorless & unreactive • Last natural elements to be discovered • Stable 8 valence e- (except He has 2 e-) • 1962 – Neil Bartlett, inorganic chemist created Xe & F compound • No known compounds for He, Ne, Ar

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