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Everything You Need To Know About Atoms

Everything You Need To Know About Atoms. (for this course). Tiny Bits. Before we talk about what atoms are made of and what they can do, you must know: They are VERY light, They are VERY small, There are VAST numbers of them. Bromide Atoms. Hydrogen on Graphene. Crystal Lattice.

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Everything You Need To Know About Atoms

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  1. Everything You Need To Know About Atoms (for this course)

  2. Tiny Bits • Before we talk about what atoms are made of and what they can do, you must know: • They are VERY light, • They are VERY small, • There are VAST numbers of them.

  3. Bromide Atoms

  4. Hydrogen on Graphene

  5. Crystal Lattice

  6. Photograph of a Single Molecule of Pentacene, used in solar cells 14 Carbon and 22 Hydrogen atoms

  7. Biggest Tiny Parts • Neutrons: N, heaviest, no electrical charge • Protons: P+,slightly less heavy, positive electrical charge • Electrons: e-, much lighter than neutrons or protons, negative electric charge • All three have a quantum mechanical quality called spin 1/2

  8. Smaller Tiny Parts • Neutrinos: n • Three kinds: electron ne, muon nm, tau nt • Weakly interactive • VERY low mass, no charge • Travel at the speed of light • (We’ll use these a little later)

  9. Atoms • Atoms have protons and electrons and, with one exception, neutrons • The simplest atom is hydrogen • 75% of the universe is hydrogen

  10. Flavors (Isotopes) of Hydrogen:Deuterium (D)--------Tritium (T)

  11. Helium • Two electrons, two protons, two neutrons • 24% of the Universe • (There is a flavor with only one neutron)

  12. As of June 2011, 114 different elements… • But hydrogen (H) and helium (He) are all we need for the most part

  13. straP yniT tseggiB • Antimatter! • Negative protons, positive electrons • Antineutrons more difficult to explain (antiquarks, CPT symmetry—not really necessary for our study) • When matter meets antimatter: annihilation! • (We’ll meet this later also)

  14. PET Scan Positron emission tomography

  15. It Takes Energy To: • Remove an electron from an atom: • Jam a proton and neutron together to make deuterium (D) • Jam an N and a D together to make a tritium (T) • Jam two Ts together to get He

  16. E=mc2 • Except for reactions that involve only electrons, nuclear processes are governed by that famous equation • It says that matter can be converted to lots of energy, and that energy can be transformed into matter • Making He out of H takes a lot of energy, but once it’s accomplished, you get more energy back

  17. Fusion • That last process is a form of fusion • Not to be confused with fission (taught in another course) • The reaction can be notated this way: T + T -> 4He + 2N • I will use this shorthand later on (and remind you of what it means)

  18. Other Examples • A reaction can emit energy in the form of a photon D + D -> 4He + g • A reaction can generate a neutrino P+ + P+ -> D + e+ + ne Don’t memorize these! They are just examples!

  19. And that’s all you need to know about atoms!

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