CHEM 121 Lecture Notes - Lecture 2: Oil Drop Experiment, Plum Pudding Model, Henri Becquerel
19 Jun 2015
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Chem121 - lecture 2 - significant figures and discovery/characterization of the atom. Will have all certain digits plus one uncertain. Definition numbers and counted numbers have unlimited sig figs (zeroes at end) 0. 0260 has 3 sig figs because of decimal. 250 has 2 sig figs because no decimal. 7 dogs has unlimited sig figs because counted number. 1. 050 x 10-3 has 4 sig figs with captive (sandwiched) zero. Adding and subtracting: answer must have same number of decimal places as whichever element has less decimal places. Multiplying and dividing: answer must have same number of sig figs as factor with least number of sig figs. Robert boyle: a substance was an element unless it could be broken down into 2 or more simpler substances. Antoine lavosier: law of conservation of mass. Joseph proust: law of definite (constant) proportions. A given compound always contains exactly the same proportion of elements by mass . Atoms of a given element are identical .
