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Atoms And Subatomic Particles

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Structure of atoms

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Atoms And Subatomic Particles

  1. 1. Atoms and Subatomic Particles
  2. 2. How big is an atom? <ul><li>An atom is incredibly small </li></ul><ul><ul><li>The diameter of an atom would have to be increased 200 million times to have the diameter of a penny </li></ul></ul><ul><ul><li>If an apple were enlarged to the size of the Earth, the atoms in the apple would be the size of cherries </li></ul></ul>
  3. 3. What is an atom made of? <ul><li>Subatomic particles: </li></ul><ul><ul><li>Neutron, proton, electrons </li></ul></ul><ul><ul><li>A central, dense nucleus (neutrons & protons) surrounded by electrons </li></ul></ul><ul><ul><ul><li>Electrons have a negative charge (-) </li></ul></ul></ul><ul><ul><ul><li>Protons have a positive charge (+) </li></ul></ul></ul><ul><ul><ul><li>Atom is held together by the attraction of electrons and protons </li></ul></ul></ul><ul><ul><ul><li>Neutrons are neutral </li></ul></ul></ul>
  4. 4. How much does an atom weigh? (What is it’s mass?) <ul><li>Atoms are so small that it is impractical to use grams </li></ul><ul><ul><li>1 atom ͌ 10 -23 g </li></ul></ul><ul><li>Instead atoms are measured in atomic mass units or amu’s </li></ul><ul><ul><li>One carbon atom is 12.0 amu’s and all atoms are compared to this </li></ul></ul>
  5. 5. Atoms - Molecules - Ions Particle Mass (kg) Mass (amu) Charge Electron 9.10939 x 10 -31 0.00055 -1 Proton 1.67262 x 10 -27 1.00728 +1 Neutron 1.67262 x 10 -27 1.00728 0 Most of the mass in an atom is in the nucleus Subatomic Particles
  6. 6. ATOMIC FACTS <ul><li>Most of the mass of an atom is in the nucleus: the protons and neutrons </li></ul><ul><li>The size of the neutron relative to the size of the atoms is like a penny in the middle of a baseball field </li></ul><ul><li>The number of protons and electrons need to be equal so that the atom has no charge </li></ul>
  7. 7. ATOMIC NUMBER <ul><li>The number of protons in the nucleus of an atom </li></ul><ul><ul><li>Atomic numbers of naturally occurring elements: </li></ul></ul><ul><ul><ul><li>Lowest=Hydrogen (H) </li></ul></ul></ul><ul><ul><ul><ul><li>Z=1 </li></ul></ul></ul></ul><ul><ul><ul><li>Highest=Uranium (U) </li></ul></ul></ul><ul><ul><ul><ul><li>Z=92 </li></ul></ul></ul></ul><ul><li>Periodic Table of Elements </li></ul>
  8. 8. ATOMIC NUMBER <ul><li>Remember, </li></ul><ul><ul><li>The number of protons in the nucleus of an atom equal the number electrons so, </li></ul></ul><ul><ul><ul><li>Atomic number= </li></ul></ul></ul><ul><ul><ul><li>Number of protons= </li></ul></ul></ul><ul><ul><ul><li>Number of electrons </li></ul></ul></ul>
  9. 9. Mass Number <ul><li>Sum of the number of protons and the number of neutrons in the nucleus of the atom: </li></ul><ul><ul><li>Mass number=# of protons + # of neutrons </li></ul></ul><ul><ul><li>And….. </li></ul></ul><ul><ul><ul><li>Mass number=atomic number + # of neutrons </li></ul></ul></ul><ul><ul><ul><li># of neutrons=mass number – atomic number </li></ul></ul></ul>
  10. 10. Isotopes <ul><li>Atoms of an element that have the same number of protons and electrons but different numbers of neutrons. </li></ul><ul><ul><li>Hydrogen isotopes </li></ul></ul><ul><ul><ul><li>Hydrogen has 1 proton, 1 electron and 0 neutrons </li></ul></ul></ul><ul><ul><ul><li>Deuterium has 1 proton, 1 electron and 1 neutron </li></ul></ul></ul><ul><ul><ul><ul><li>Therefore, it is heavier than hydrogen but has similar chemical properties and slightly different physical properties </li></ul></ul></ul></ul><ul><ul><ul><li>Tritium has 1 proton, 1 electron and 2 neutrons </li></ul></ul></ul>
  11. 11. Atomic Masses <ul><li>Atomic mass ͌ Mass number </li></ul><ul><ul><li>They are close but not the same </li></ul></ul><ul><li>Here’s why </li></ul><ul><ul><li>Mass number is an exact number & atomic mass is a weight so it’s an inexact number </li></ul></ul><ul><ul><ul><li>Hydrogen has a mass number of 1 (1 protron + 0 neutrons), </li></ul></ul></ul><ul><ul><ul><li>But weighs: 1.00728 amu </li></ul></ul></ul><ul><ul><li>Atomic masses are calculated based on the percentage of isotopes present in natural world </li></ul></ul><ul><ul><ul><li>H=99.985%; D=.015%; T=trace </li></ul></ul></ul><ul><ul><ul><li>Atomic mass of H is: 1.00794 </li></ul></ul></ul><ul><ul><ul><li>Periodic table of elements </li></ul></ul></ul>
  12. 12. Chemical Basis of Life <ul><li>Most common elements in living organisms </li></ul><ul><ul><li>Carbon (C): 9.5% </li></ul></ul><ul><ul><li>Hydrogen (H): 63% </li></ul></ul><ul><ul><li>Oxygen (O): 25.5% </li></ul></ul><ul><ul><li>Nitrogen (N): 1.4% </li></ul></ul>
  13. 13. Macrominerals <ul><li>Minerals we need a lot of </li></ul><ul><ul><li>Calcium ( Ca ) </li></ul></ul><ul><ul><li>Phosphorous ( P ) </li></ul></ul><ul><ul><li>Magnesium ( Mg ) </li></ul></ul><ul><ul><li>Potassium ( K ) </li></ul></ul><ul><ul><li>Sodium ( Na ) </li></ul></ul>
  14. 14. Microminerals <ul><li>Needed in small quantities </li></ul><ul><ul><li>Iron ( Fe ) </li></ul></ul><ul><ul><li>Copper ( Cu ) </li></ul></ul><ul><ul><li>Chromium ( Cr ) </li></ul></ul><ul><ul><li>Fluoride ( F ) </li></ul></ul><ul><ul><li>Iodine ( I ) </li></ul></ul><ul><ul><li>Selenium ( Se ) </li></ul></ul><ul><ul><li>Molybdenum ( Mo ) </li></ul></ul><ul><ul><li>Zinc ( Zn ) </li></ul></ul>

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