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Unformatted text preview: Lecture 1 Basic parts of an atom include the following: 1) Nucleus: contains nucleons which are either protons or neutrons or both 2) Electrons: electrical particle far from nucleus with very small mass compared to nucleons Neutrons posses no electrical charge, while protons are positively charged (both have mass of 1) Electrons are very small, low mass electrically charged particles but they have negative charge, thus they are attracted to protons in the nucleus Electrons are active agents in bonding one atom to another, whereas protons are the active agents in holding electrons within the atom Proton number determines which element we are talking about Different numbers of neutrons determine the isotope of the element in question There are 92 naturally occurring elements Titanium #22, Manganese #25, I ron #26, Copper #29 Sterling Silver 92.5% Silver, 7.5% Copper 14k gold = 56/100 = 14/24 56% Gold, 44% Silver White gold is mixed with palladium Minerals and other chemical compounds are structures in which electrical charge is neutral throughout the volume of the crystal (this is why you get 0 when charges are added up. Ex SiO 2 ) Fi rst step in crystallizat ion: chemical bond formed by interaction of electrons among atoms Second step in crystallizat ion: form an atom ic latt ice called unit cell for solids building block Lecture 2 A major building block in silicate minerals is silicon tetrahedron ( 1 Si (+4), 4 O (-2)) Net charge -4 When 2 silicon tetrahedrons combine they share the middle oxygen (Nesosilicate) Net charge of -6 Result of using all silicon tetrahedrons to build a structure is SiO 2 the mineral quartz In a crystal all the corner oxygens are shared (tectosilicate) Aluminum octahedron ( 1 Al (+3) , 6 O (-2)) Net charge of -9 Peridot ((Fe,Mg) 2 SiO 4 ) isolated silicon tetrahedron nesosilicate Ilvaite (CaFe 3 Si 2 O 8 (OH)) double islands sorosilicate Pectolite (Ca 2 NaH(SiO 3 ) 3 ) parallel single chains of silicon tetrahedral...
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- Fall '08