CHEM 1A Lecture Notes - Lecture 2: Plum Pudding Model, Mass Spectrometry, Atomic Mass

• School: UC-Irvine
• Department: Chemistry
• Course: CHEM 1A
• Professor: Penner

Document Summary

Mass of products equals the mass of the reactants. Electrons scattered randomly in a sphere of positive charge. Atoms and elements originated from the big bang theory, starting with hydrogen and helium! Sum of protons and neutrons of an atom. Atomic mass= (fraction of isotope)(mass of isotope) In a neutral atom, the number of protons is equal to the number of electrons. If the element/atom is a cation, subtract electrons. If the element/atom is an anion, add electrons. Sample is heated, ionized, and passed through a magnet and reflected in order to measure the bend. Heavier elements bend less, while lighter elements bend more. Significant figures (2-3 sig figs, but remember to apply the rules depending on whether you"re adding/subtracting or multiplying/dividing) Error with equal probability of being too high or too low. Error that doesn"t average out with repetition. All data fall in the same area. Tens place less precise than hundredths place.