CHEM 101A Lecture Notes - Lecture 2: Atomic Radius, Ion, Periodic Trends
8 Sep 2016
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Document Summary
Of the 118 known elements 90 are naturally occurring and 28 were made by scientists. The position of an element on the periodic table is based on its chemical properties. Divided into three categories- metals, nonmetals, and metalloids. Metals are to the left of the zigzag line starting at b (boron) and ending at at (astatine) All non metals, except hydrogen, are to the right. Metals: shiny that conduct heat and electricity, ductile- can be drawn into wires- malleable. Nonmetals: poor conductors of heat and electricity. Metalloids: have properties between metals and nonmetals. Four nonmetal elements- oxygen, carbon, hydrogen, and nitrogen. Carbon, hydrogen, and oxygen found in 4 main types of biological molecules- protein, carbs, nucleic acid,lipids. Nitrogen is in protein and nucleic acid. They make 96% of the mass of the human body. Sodium, potassium, and chlorine- present in body fluid. Calcium & phosphorus- in teeth and bones. At least 100mg of macronutrients are needed daily.
