chem lecture 3

chem lecture 3 - Warm-Up Clicker Questions Chemistry 6A 1...

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Chemistry 6A Warm-Up Warm-Up Clicker Questions Clicker Questions 1
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Chemistry 6A 2 The ELEMENTS: A First Glance The ELEMENTS: A First Glance The Periodic The Periodic Table of the Table of the Elements Elements “The Periodic Table” Animation by Thomas Poon (Claremont McKenna College) set to Tom Lehrer’s “The Elements” (1995)
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Chemistry 6A How Many Elements Occur Naturally? There are 111 authenticated elements, of which 88 are naturally occurring , with uranium being the element of highest atomic number (Z = 92). Despite the fact that all nuclides with Z >/= 83 are radioactive, uranium is naturally occurring because it has 2 isotopes ( 235 U and 238 U) with half-lives (700 million years and 4.5 billion years, respectively) that are on the order of the Earth’s age. Elements 43 (Tc) , 61 (Pm) , 85 (At) and 87 (Fr) have no stable isotopes, and none of long half-life, so they are not naturally present. These “ synthetic elements ” are only known on Earth as the product of nuclear reactors or particle accelerators; or as byproducts from nuclear explosions. 3
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Chemistry 6A … And other Elemental Points! And elements 112, 113, 114, 115, 116 and 118 have not been granted official status by IUPAC. October 16, 2006: Experiments reported that 3 atoms of element 118 (t 1/2 = 0.89 msec) had been produced. In 2001 , the earlier claims of Uuo were retracted. Element 117 has not been observed! Not all elements occur in the “Free” state! In the early 1800s Sir Humphrey Davies pioneered the use of electricity from the Voltaic pile to decompose the salts of alkali metals. Many other elements have been isolated from mineral deposits. Emission spectroscopy helped to identify many elements! For example, He was discovered by astronomers as an emission line from the sun 30 years before it was found on Earth. 4
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Chemistry 6A Elements at the Earth s Surface* Oxygen 49 Silicon 26 Aluminum 7.5 Iron 4.7 Calcium 3.4 Sodium 2.6 Potassium 2.4 Magnesium 1.9 Hydrogen 0.88 Titanium 0.58 Chlorine 0.19 Others 0.56 % by mass * includes oceans and atmosphere • Crust oxides include SiO 2 , Al 2 O 3 , CaO, MgO, Na 2 O, FeO, K 2 O, Fe 2 O 3 5
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Chemistry 6A Elements in the Human Body Oxygen 65 Carbon 18 Hydrogen 10 Nitrogen 3 Calcium 1.5 Phosphorus 1.0 Potassium 0.35 Sulfur 0.25 Sodium 0.15 Magnesium 0.05 Cu, Zn, Se, Mo, F, Cl, I, Mn, Co, Fe 0.70 Li, Sr, Al, Si, Pb, V, As, Br Trace % by mass • Most of the body is made up of H 2 O • Carbon is the basic building unit for organic molecules 6
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The Modern Periodic Table Categories of Elements Elements arranged in groups (columns) possess related chemical and physical properties. The elements in periods (rows) possess progressively different chemical and physical properties. Groups of elements with similar properties
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chem lecture 3 - Warm-Up Clicker Questions Chemistry 6A 1...

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