CHEM 100 Chapter Notes - Chapter 2: Atomic Mass, Electron Configuration, Atomic Number
Document Summary
2. 1 chemical background for the early atomic theory. Law of constant composition the elements present in a compound are present in fixed and exact proportion by mass, regardless of the compound"s source or method preparation. Percent composition specified as the mass percent of each element. Element a substance in which all the atoms have the same atomic number and electron configuration. Compound a pure substance composed of atoms of two or more elements present in a fixed and definite ratio. Dalton"s model explained why the elements in a compound are present in fixed and exact proportion by mass. According to dalton, the principal difference between different elements is the different masses of their atoms. Dalton compared the masses of other elements with the mass of hydrogen in each compound and established the relative atomic masses. Relative masses of atoms are determined by mass spectrometry. Atomic masses relative to the mass of the most common isotope of the element carbon,
