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Atoms, Ions and the Periodic Table. Chemistry 131 Chapter 2. Dalton’s Atomic Theory. Structure of the Atom. Atomic Mass. Periodic Table. Ions. Dalton’s Atomic Theory. Two Key Ideas led to Atomic Theory. Law of Conservation of Mass. 1787 - Lavoisier. Law of Definite Proportions.
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Atoms, Ions and the Periodic Table Chemistry 131 Chapter 2
Dalton’s Atomic Theory Structure of the Atom Atomic Mass Periodic Table Ions
Law of Conservation of Mass 1787 - Lavoisier
Law of Definite Proportions 1804 - Proust
Published in 1808 with Four Postulates Dalton’s Atomic Theory
All matter is composed of exceedingly small, invisible particles called Atoms.
Atoms of an element have a given mass and properties, atoms of differing elements differ in mass and properties.
Atoms combine is simple, fixed, whole-number ratios to form compounds
Positive Charge Thomson’s discovery of the electron posited a different model. Negative Charge Electron
Rutherford’s Gold Foil experiments led to yet another revision
Proton Mass = 1.6726×10-24 gCharge = +1.6022×10-19 C
Neutron Mass = 1.6749×10-24 g Charge = 0
Electron Mass = 9.1094×10-28 g Charge = -1.6022×10-19 C
Atomic Number = Number of protons Mass Number=#Protons + # Neutrons
Isotopes Hydrogen Also Hydrogen
Number of Electrons = Number of Protons, if the atom is neutral.
Ions +1 Li
The atomic masses on the periodic table are relative atomic masses
Relative Atomic Mass=(Isotope 1 mass × Abundance 1) +(Isotope 2 mass × Abundance 2)+…
Example (Silver)107Ag 106.9051 amuis 51.82%109Ag 108.9048 amuis 48.18%
106.9051 amu × 0.5182 = 55.40 amu108.9048 amu × 0.4818 = 52.47 amu55.40 amu+52.47 amu =107.87 amu
Problem Given the following information, calculate the relative atomic mass of Magnesium. 24Mg = 23.985 amu at 20.00% 25Mg = 24.985 amu at 20.00% 26Mg = 25.983 amu at 60.00%
Problem The copper mined on Earth consist of 63Cu (62.93 amu) and 65Cu (64.93 amu). Which isotope is more abundant? Why?
Review Problem 1 How many carbon atoms are present in each sample? 120 amu 12,000 amu 7.22 × 1024amu
Review Problem 2 During a typical physical exam blood tests measure the cholesterol level. A high result is anything over 240.0 mg/dL. What is this in pounds/fluid ounce? If a typical human has 5.000 L of blood, how many pounds of cholesterol are present in the blood of a patient with a total cholesterol of 260.0 mg/dL?