Chemistry 18-20 Outlines

Chemistry (Hm Chemistry College Titles)

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Kanav Jain 12/24/2007 Cass 3 Chapter 18 I. A Survey of the Representative Elements A. Atomic Size and Group Anomalies 1. Chemical properties determined by valence s and p electrons 2. Dramatic difference between 1 st member and rest due to size a) Hydrogen is very small, much greater attraction for electrons than do larger members b) First member always forms strongest pi bonds (1) Elemental nitrogen and oxygen to exist as N2 and O2, while phosphorus and sulfur as P4 and S8 (2) Hydrogen vs. 1A (a) Forms covalent bonds with nonmetals rather than ionic bonds (3) Beryllium vs. 2A (a) Covalent bonds with nonmetals rather than ionic bonds (4) Boron vs. 3A (a) Nonmetal, others are metals (5) Carbon vs. 4A (a) Readily achieves octet by forming pi bonds with oxygen in CO2 (b) Silicon does not form pi bonds with oxygen in SiO2 (6) Nitrogen vs. 5A (a) Nitrogen forms N2 with pi bonds (b) Phosphorus forms P4 tetrahedral with single bonds (7) Oxygen vs. 6A (a) Diatomic with pi bonds (b) Sulfur forms cyclic S8 with single bonds (8) Halogens (a) Chlorine has unusually higher EA than fluorine B. Abundance and Preparation 1. Most abundant element – oxygen, 2 nd silicon 2. Most abundant metals – Aluminum, 2 nd iron a) Found in ores combined with nonmetals, most commonly oxygen 3. Most abundant in human body – Oxygen, carbon 2 nd 4. Metallurgy a) Obtaining metal from ore (1) Usually carbon as reducing agent (2) Tin uses hydrogen as reducing agent b) Electrolysis (1) Highly active metals 5. Purification of nonmetals
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a) Liquefaction (1) Expansion and compression (2) Electrolysis (3) Decomposition II. The Group 1A Elements A. Valence electron configuration ns1 B. All but hydrogen lose one electron readily to form M+ ions C. React vigorously with water to form M+ and OH- ions and hydrogen gas D. Form oxides with oxygen 1. Regular oxide formed by lithium 2. Sodium forms peroxide in excess oxygen 3. Potassium, rubidium, cesium form superoxides MO2 E. Biological importance 1. Na+ and K+ important to nerve conduction and muscle contraction 2. Li+ affects neurotransmitter levels, treats bipolar disorder III. Hydrogen A. Colorless, odorless B. Low boiling and melting points C. Highly flammable D. Purification 1. Decomposition of methane in water using heat, pressure, catalyst 2. Cracking of hydrocarbons in gasoline production E. Industrial Use 1. Ammonia production by Haber process 2. Hydrogenating unsaturated vegetable oils F. Covalent bonds with nonmetals G. Salts with very active metals H. Binary compounds – hydrides 1. Ionic hydrides a) Hydrogen combines with 1A, 2A metals 2. Hydride ion a) Strong reducing agent 3. Covalent hydrides a) Hydrogen combines with other nonmetals 4. Metallic hydrides a) Hydrogen atoms migrate into transition metal crystals IV. The Group 2A Elements A. Valence configuration ns2 B. Alkaline earth metals 1. Basicity of their oxides C. First member beryllium has amphoteric oxide D. React less vigorously with water than do alkali metals 1. Beryllium and magnesium do not react with water at 25 celsius
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Chemistry 18-20 Outlines - Kanav Jain 12/24/2007 Cass 3...

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