The Periodic Table

5. The Periodic Table • All about pure substances • Cannot be broken down to another substance • Middle Ages alchemists suspected • First list of 30 published in 1793 by Antoine Lavoisier • Some were compounds not yet decomposed • Dalton in 1803 • His list also contained some compounds • Eventually revised to 60 elements

6. The Periodic Table • Element periodicity • Johann Dobreiner’s triads • When arranged by atomic mass, groups of 3 with similar properties emerged • Cl, Br, I – all gases with similar color & properties • “Family” concept important first step in discovery of periodicity • Newlands – 1864 – still arranged by mass, but discovered that elements grouped into 7 columns • Called “law of octaves” based on musical octave • Idea of atomic mass relating to chemical properties correct, but needed more study

7. The Periodic Table • Mendeleev’s periodic law – “properties of elements vary with their masses in a periodic way.” • Documented existing and predicted unknown elements How often did Mendeleev tell chemistry jokes? Periodically.

8. The Periodic Table • Table still needed refining • Moseley – using X rays able to count protons • When arranged by atomic number clear patterns emerged • New periodic law • Properties of elements vary with atomic number in a periodic way • Transition elements because of similar properties were difficult to isolate • Invention and use of mass spectograph – sorts using electrical charges - helped to isolate – all but promethium placed by beginning of WWII

9. The Periodic Table • Structure of the table • Symbol/name • Atomic number • Radioactivity • Average atomic mass • Electron configuration • Rows – periods or series – highest principal energy level • Columns – groups or families – similar characteristics • IUPAC convention – 1-18 • North American Convention – number and letter 1A – valence electron structure • Transition metals – exceptions to electron configuration rules – B • Inner transition metals – Lanthanide and Actinide grp – no system • www.ptable.com

10. The Periodic Table • Arrangement of the table reflects electron structure of atoms • Various measureable properties that vary with periodic number • Atomic Radius • Center of atom’s nucleus to outermost electron • Electrons attracted by protons • Repelled by other atoms’ electrons • One property that shows periodicity is atomic radius

11. Atomic Radius • Radii Rules: Down table Increase • Across Table – decrease • Why? • All about the . . . • As move down – adding energy levels – radius increases • Every added proton doubles positive attraction • Across - adding electrons inside outermost N doesn’t affect energy level – size not as affected

12. Atomic Radius

13. Ionic Radii • Cations • Larger positive charge holds electrons tighter • Metals tend to make cations • Anions • Larger negative charge pushes electrons away from nucleus and away from each other

15. Ionization Energy • A second property that varies with periodicity • First Ionization Energy - The energy required to remove the first electron from its outer shell—making a cation • Generally increases left to right • As nucleus gets larger – electrons held stronger • Decreases top to bottom • As atoms get larger – electrons further from nucleus—held weaker • Ionization energy clearly related to atomic radius • Smaller radius – larger energy needed • Larger radius – smaller energy needed

16. Ionization Energy

17. Electron Affinity • A third property that varies with periodicity • Electron Affinity – amount of energy required to add an electron to a neutral atom to form an anion • Opposite of 1st ionization energy • Measures how strongly an atom attracts additional electrons • Most affected by fullness of outermost energy level • Full outermost sublevel – electron repelled – unless energy is expended to move an electron to a higher sublevel • Groups 2/12/18 • In general become larger left to right • Again, strongly related to atomic radius • Smaller radius – better it attracts electrons—if room in outer shell • Top to bottom depends on location • S & P blocks tend to decrease slightly from top to bottom

18. Electron Affinity

19. Electronegativity • A fourth property that varies with periodicity • Electronegativity – measure of attraction between nucleus and valence electrons • Ability to attract and hold electrons in a molecule • Determined mathematically instead of experimentally • Linus Pauling’s electronegativity values • Fluorine holds strongest (value 4) - Cesium weakest • Computed all other values based on these two • Electronegativity increases from left to right in a period • Again, smaller atom, greater ability to hold electrons • Electronegativity decreases from top to bottom in a group • Larger atom, less ability to hold electrons

20. Electronegativity

21. Element Families • Hydrogen – its own family • Most abundant –MW gas 90% hydrogen • Electron config same as alkali metals • Properties of non-metals • Family of its own

22. Element Families • Henry Cavendish–first to systematically collect & study-called it “inflammable air” • Lavoisier – named hydrogen “water former” because produces water in air • Colorless, odorless, tasteless, diatomic • Moves at very high speed in atmosphere • Very low condensation pt (-253C) and freezing point (-269C) – almost absolute 0

23. Element Families • Chemical Properties • Extremely reactive and explosive when oxidized • H & O power space shuttle • NH3 – ammonia – fertilizer and homemade bombs • Acids when combined with grp 17 (HCl) • Hydrides when combined with alkali metals • LiH coats nuclear reactors as a radiation barrier • Also used to store hydrogen since can be readily removed with water • Hydrocarbons – very common fuels • Methane, propane, butane Hydrogen (version 1) - Periodic Table of Videos - YouTube

24. Element Families • Alkali Metals • Properties first isolated by Sir Humphrey Davy • Na most abundant – 6th most common element • Francium most rare - <2g in world • Physical properties • Very lustrous, but oxidize rapidly • Low density – many less than water • Very soft at room temp • Chemical properties • Single valence electron makes highly reactive

25. Element Families • Alkali Metals • Chemical properties • Single valence electron makes highly reactive • Donate single electron readily • Highly reactive with water • None naturally found in pure form • Uses–streetlights–Na vapor lamps • Salt, baking soda, rayon, paper • K-fertilizers, soaps, glass, explosives • Ce – atomic clocks • Li – water-resistant lubricants, batteries

26. Element Families • Alkaline Earth Metals • Grp 2 – all solids at room temp-metallic props • Denser, harder, higher melting pts than Alkalis • From cations w/+2 charge • Loss of 2 electrons gives them filled valence shell • Be – important in many minerals • Makes emeralds green • Mg – 8th most common – important in chlorophyll • Ca – 5th most common element on earth • For strong bones and teeth drink your milk, son! • Sr, Ba, Ra-radioactive & luminescent

27. Element Families • Alkaline Earth Metals • Physical properties • Freshly cut, bright silvery to white – quickly oxidize to dull gray or yellow • Slightly more dense than alkali but much harder • All malleable • Chemical properties • Two electrons in outermost sublevel • Combine with nonmetals, donating these 2 electrons • More reactive as go down group • Be no react w/water, Mg with steam, Ca vigorous reaction

28. Element Families • Alkaline Earth Metals • Uses • Be – xray tubes, xparent to low energy xrays • Mixed to produce many critical alloys • Mg – lightweight alloys – fireworks, flares • Compounds – Mg (epsom) salts and milk of magnesia (MgOH) • stomach soothing • Ca – seashells: limestone • Sr –blocks Xrays – used in old CRT TVs • Brilliant red flame for flares and fireworks • Ba – fireworks, rat poison, rubber, linoleum, medical xrays of gastrointestinal tract • Ra – treat specific forms of cancer • Alkaline and Alkaline Earth Metals – YouTube • http://www.youtube.com/watch?v=B2ZPrg9IVEo&feature=related

29. Element Families • Meet the Elements • Metals • Make up largest part of periodic table • Transition metals – d block (d sublevels) • Inner transition metals – f block (f sublevels) • Transition metals • Old theory – characteristics change gradually to metalloids/nonmetals • Still has validity due to placement on periodic table • Most common – iron, copper, titanium, chromium • Most precious – silver, gold, platinum

30. Element Families • The titanium bathtub – The A-10 Tunderbolt • Cockpit • The single-seat cockpit is protected by all-round armour, with a titanium 'bathtub' structure to protect the pilot that is up to 3.8cm thick. The cockpit has a large bulletproof bubble canopy, which gives good all-round vision.

31. Element Families • Physical Properties • Dense, hard, strong • Shiny, conductive, ductile, malleable • Most exhibit magnetic properties • All except Hg solid at room temp • Chemical Properties • Most similar due to d sublevel electrons • Due to quantum mechanical relationships between electron structure & nuclear charges • Little difference between outer S sublevel and d sublevel just beneath it • Allows electrons to jump back and forth with little energy and combine easily

32. Element Families • Countless uses • Frames, shells, engines, Ferraris • Alloys – hip joints, coins, jewelry • Electrical wire • Most forms of life require trace amounts • “Your iron is low” – most often causes anemia • Hemoglobin in blood • High concentrations are harmful

33. Element Families • Inner transition metals • Lanthanide/Actinide series • F orbitals period 6/7 but orbitals 4f/5f • Rare earth metals – hard to isolate and identify • Thorium (Z=90) to Lawrencium (Z=103) • Only first 5 of Actinide series found in nature • Yttrium/Scandium sometimes included due to similar props • Physical Properties • Paramagnetic – weakly attracted by a magnetic field due to unpaired electrons • All Lanthanides found in nature except Promethium • Bright, silvery

34. Element Families • Chemical Properties • Great uniformity • Difficult to purify from ores • Usually give up valence electrons and some f sublevel when combining • Not usually harmful to health due to low concentrations • Actinide series radioactive – emit tissue destroying/cancer causing rays & particles • Used in glass, TV tubes, catalysts for chemical reactions • Actinide series – bombs, nuclear power • The Tsar Bomba – largest ever uranium bomb

35. Element Families • Post transition Metals & Metalloids • P/T metals: the stairstep group beyond the transition metals • Well known elements like Al, Sn and Pb as well as obsure like Ga and Tl and In • Metalloids: live on the stairs between metals and nonmetals • Luster, hardness, conductivity, chemical reactivity between metals and nonmetals • B, Si, As, Sb, Ge, Te, At • Less than 30g At worldwide • Semiconductors

36. Element Families • Boron family • Boron – metalloid very different from 5 metals below • Al, Ga, In, Tl, Uut • Most economically important-B & Al • The Boron rap • Al – strong, light, very malleable and shapeable • Used everywhere from power lines to aircraft to coke cans to honeycomb surfboards • Most common metal in earth’s crust • Al’s archenemy – mercury • Other Gp 13 metals very metallic • Gallium – melts in your hand and attacks Al as well • http://www.youtube.com/watch?v=FaMWxLCGY0U

37. Element Families • Chemical properties • Al – too chemically reactive to find alone • Usually Bauxite – Al2O3 • Corrodes in presence of O • However, Al oxide forms an impenetrable shield preventing further oxidation – called anodized aluminum • Fairly soft but alloys with many other metals to make it useful • Uses of Boron family • Boron used in fiberglass – boric acid to treat injuries, borax as soap, absorb neutrons in reactors

38. Element Families • The Carbon Family • 1 nonmetal (C) two metalloids, Si & Ge and two metals, Sn and Pb • Carbon most important element for all life • Biological compounds are mostly carbon compounds • Biochemistry and organic chemistry study carbon compounds • Physical properties • All C forms have 4 valence electrons but combines differently with different atoms • CO2 and CO for example • Si does not react with air water or acids easily • Snrealatively inactive, used to coat other more reactive metals such as copper • Lead very inactive especially with acids

39. Element Families • The Carbon Family • 1 nonmetal (C) two metalloids, Si & Ge and two metals, Sn and Pb • Carbon most important element for all life • Biological compounds are mostly carbon compounds • Biochemistry and organic chemistry study carbon compounds • Physical properties • All solids at room temp • Carbon – soft, dull, black like graphite or coal or hard and shiny as diamond – depends on crystalline structure • Si and Ge – brittle solids with metallic luster • Tin – white or gray metal, malleable and somewhat ductile • Lead – soft gray metal, very malleable and ductile

40. Element Families • The Carbon Family • Chemical properties • All C forms have 4 valence electrons but combines differently with different atoms • CO2 and CO for example • Si does not react with air water or acids easily • Snrealatively inactive, used to coat other more reactive metals such as copper • Lead very inactive especially with acids • Uses – Carbon – electrodes, lubricant as graphite, pencils, gemstones, drills and abrasives • Semiconductors (Si, Ge) vital to microprocessor industry • The making of the AMD microchip • Sn forms with copper to make bronze- corrosion proof plumbing, statues • Pb – batteries in our car, shielding for xrays and around nuclear reactors and weapons

41. Element Families • The Nitrogen Family • Group 15 – dramatic range of properties • N – a gas, four solids; P, As, Sb, Bi, and Uup • N & P – nonmetals, As, Sb – metalloids, Bi, Uup, P/T metals • All have 5 valence electrons and transfer or acquire as needed in combining with other elements • 1772 – Daniel Rutherford first recognized N, and showed it is not life-sustaining like O or CO2 for plant • P discovered ~100 yrs prior by German • Distilled a substance that glowed in dark – Lavoisier named phosphorus – light bearer • As may have been discovered as early as 1250 • Very poisonous

42. Element Families • The Nitrogen Family • Normally diatomic N2 gas – colorless, odorless, tasteless – 78% of the atmosphere • P – not found as native element—too reactive • Red, yellow, black, white • White is phosphorescent • Chemical properties • N is essentially inert. Atoms tightly bound-tough to split up – combines only under high temps • P very reactive – burns spontaneously in atmosphere • Poisonous even in small amounts

43. Element Families • The Nitrogen Family • Uses – N used to create inert environments for manufacturing electronics, welding, forcing oil to the surface, eliminate explosive hazards and production of ammonia, NH3 • P – matches, fireworks, flares, fertilizer. Phosphoric acid – makes many compounds - and alloys • As additive to microprocessor chips for etching, preserve animal skins, manufacture glass • Sb – semiconductor applications – makes glass heat resistant • Nitrogen Triioddide

44. Element Families • The Oxygen family • Physical Properties • O – colorless, odorless, tasteless – 21% of atmosphere • Slightly water soluble, most abundant by mass in crust • Enough dissolves in water to sustain life there • Exists in atmosphere as O2 and O3 (ozone) • Ozone has a pungent smell – lightning creates it • Screens most of the harmful UV rays • S – Variety of forms based on atomic arrangement • Native S – solid, brittle, yellow crystal • At 115C melts and crystallizes into another form • Pour into water, makes amorphous globs

45. Element Families • The Oxygen family • Chemical Properties • S and O have similar • O one of most reactive – electronegativity second only to fluorine – strong attraction for electrons makes it react with nearly every element to form oxides • S – reactive at room temps, but not as much as O • Metals like Sn, Ca, Fe combine to form sulfides • Combines with O and halogens to form SO2,, SCl2, SBr2 • Liquid sulfur in presence of pure O2 burns • Uses • O supports combustion, necessary for all life • Except anaerobic bacteria • Hundreds of thousands of compounds – rockets • S – makes rubber strong – many compounds • H2SO4 + C12H22O11 (Sucrose) = 12c + H2SO4 +10H2O • Carbon snake • Selenium – photocopying, dandruff, semiconductors, photo cells • Polonium – power source due to radioactivity, static electricity

46. Element Families • The Halogens • Called because form salts when react with metals • Very reactive – hard to obtain and keep • F, Cl, Br, I, At – all nonmetals except At • F – electronegativity > any other – tough to separate • ID’d in 1886 – one of last halogens to be discovered • Cl – Recognized in 1771 – Cl means green in Greek • Br – only nonmetallic liquid at room temp – irritating, poisonous vapor stinks – Greek bromos – stench (1826) • I – 1811 – seaweed + sulfuric acid gave off violet vapor that crystallized when cooled • Joseph Gay-Lussac named after Greek for violet • At – name means unstable – highly radioactive, no stable isotopes • Only metalloid in halogen family

47. Element Families • The Halogens • Physical properties • AS atomic numbers increase, density, melting points increase and colors show darker hue • F – pale yellow gas, Cl denser, greenish-yellow gas, Br, deep reddish-brown liquid, I grayish black crystalline solid • Chemical properties • Large electronegativities, there high reactivity • In pure form, diatomic molecules • Form acids when combined with H • Form salts when combine with metals • Very adept at taking electrons (7 valence) form compounds easily • F – very reactive – ignites when exposed to water • With metals forms protective layer of metallic fluoride – protects from further corrosion – fluorine reactions • Other halogens similar though less reactive – poisonous to humans

48. Element Families • The Halogens • Uses • F - Nonstick cookware, acids for etching glass, fluoride to strengthen tooth enamel • Cl – Laundry bleach, swimming pools, bleach wood pulp in making paper and of course NaCl • Br – photographic compounds, spas, natural gas and oil production • I – very important physiologically, lack of in body stunts growth and causes enlarged thyroid (goiter) • Radioactive isotope used to treat thyroid cancer • With O, disinfectant and oxidizing agent – with potassium in photography • At – no significant uses – very rare, radioactivity makes difficult to handle • Al & I reaction

49. Element Families • The Noble Gases • The most stable (octet filled) – do not react except under extreme conditions of pressure/temp • Argon separated from N in atmosphere by Lord Raleigh and Sir William Ramsay in 1894 – 1st noble gas isolated • He – in spectrogram of sun in 1868 – Id’d on earth in 1895 by Ramsay • Kr “hidden element”, Xe “stranger”, and Rn all isolated by scientists • Rn byproduct of radioactive decay • Uuo – synthetic – so radioactive only exists for less than one millisecond

50. Element Families • The Noble Gases • Physical properties • All colorless, odorless, tasteless gases • Extremely low boiling and freezing points • High energy atoms with little attractiveness for each other • Chemical properties • Avoid combining with other elements • Scientists have forced some short-lived combinations but not with Ar or Ne