CHEM 200 Chapter Notes - Chapter 2: Hydrogen Peroxide, Sodium Chloride, Covalent Bond

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The total mass of substance does not change during a chem reaction. A specific compound is made of the same elements in the same proportion. If elements a and b react to form 2 different compounds, the ratio a:b in each can be expressed as simple ratios. 1909- millikan measured the charge of the electron. 1910- rutherford demonstrated that the atom contained a tiny nucleus of positive charge that contained most of the mass of the hydrogen atom. 1932- chadwick discovers a neutral subatomic particle called the neutron which has about the same mass as hydrogen. Atoms of an element with the saame # of protons, but with different # of. Cl35 = 34. 69 amu abundance = 75. 35% 37cl = 36. 966 amu abundance= 24. 65% R1 + r2 p1 + p2. # of atoms on both sides must balance. # of moles of each element must balance. Write the skeleton equation (x y) Cu (s) + s8 (s) cu2s(s)