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3. Pwpt The Atom


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3. Pwpt The Atom

  1. 1. The Atom<br />Unit III<br />
  2. 2. Picture it….<br />Draw a picture of a Helium particle and a Xenon particle.<br />Similarities: Both are atoms.<br />Difference? Mass <br /> He: 4.0 g/mole<br /> Xe: 131 g/mole <br />
  3. 3. Why???<br />Xenon has more stuff in it. <br />So, what’s in an atom?<br />Protons = positive charge =p+<br />Electrons = negative charge = e-<br />Neutrons = neutral charge = n0<br />Now, draw a picture of the Helium atom, show how the subatomic particles are arranged.<br />
  4. 4. The Helium Atom<br />= proton<br />= neutron<br />= electron<br />
  5. 5. Atomic Number (Z):<br />Identifies the element.<br />Number of protons. <br />Whole number (Blue) on periodic table.<br />For a neutral atom the # of protons is equal to the number of electrons.<br />
  6. 6. ISOTOPES: Atoms that have the same number of protons but different number of neutrons.<br />Mass Number (A):<br />Unique for each isotope. <br />Number of p+ + number of no<br />Not found on periodic table.<br />C-12 vs. C-14<br />
  7. 7. Identify the # of subatomic particles<br />
  8. 8. Atomic Mass:<br />Also called atomic weight or molar mass.<br />Weighted average mass for one mole of all isotopes.<br />Decimal number found on P.T.<br />Atomic Mass = (mass1)(relative abundance1) + (mass2)(relative abundance2) +………..<br />
  9. 9. Example: Calculate the atomic mass of chlorine. The two isotopes have atomic masses and relative abundance of 34.97 amu (75.77%) and 36.97 amu (24.23%). <br />