Atoms and Molecules by 2CB8JK


									                                                                   Carbon Monoxide
Atoms and Molecules                                                  C      O
 Atoms: The smallest units of each chemical element.

 Positively charged protons and neutral neutrons in the nucleus.
 Negatively charged electrons around the nucleus.
 A single grain of sand can contain 10 million billion atoms.

 92 different atoms in nature, from hydrogen (H, 1 proton) and
 helium (He, 2 protons) up to uranium (U, 92 protons).

 Molecules: Made of several atoms bound together by
 electric forces.
                          Internal Energy for Atoms/Molecules
•Mass: Changes in nuclear reactions, and different atoms (nuclei) can be produced.
•Electric potential energy: Depends on how far the electrons are from the nucleus.
•Kinetic energy: In the motion, rotations, and vibrations of atoms and molecules.
•Gravitational potential energy: Plays a large role over astronomical distances.

•Big surprise, Quantum Physics: Each kind of atom or molecule can only be in certain
                                    specific states!
•When electrons change state, light can be emitted (electron loses energy) or absorbed
                               (electron gains energy).
        UNR is Plasma Physics Central!!
•Plasma is a partially ionized gas. Electrons are ripped from their atoms.
•Some electrons are free rather than being bound to an atom or molecule.
•Positive and negative charges move somewhat independently. Plasma is
electrically conductive so that it responds strongly to electromagnetic fields.
•Plasma has properties quite unlike those of solids, liquids or gases and is
considered to be a distinct state of matter.
•Plasmas are the most common phase of matter in the universe, by mass
and volume.
•All stars are made of plasma.
•Colors are from electrons relaxing to lower energy states when they
recombine with ions.
•Light color is characteristic of the atoms or molecules in the gas.
                   Plasma Physics and the Earth

                                                         Photo of aurora borealis

As the speeding solar wind hits the Earth's magnetic field, it creates a shock wave,
compresses the forward side of the field, and stretches the far side into a long
magnetotail. The field traps particles into the donut-shaped Van Allen radiation belts,
which then protect the Earth against the wind. The interaction of the wind and the Earth's
field generate two rings of electrical current that flow around the magnetic poles (which
are offset relative to the rotation axis) and that in turn create the aurora borealis. (From
Stars, J. B. Kaler, Scientific American Library, Freeman, NY, 1992.)
Ranges of Plasma
  Plasma Propulsion for Deep Space Exploration


•Ion thruster uses plasma in some part of the thrust generation process.

•Much less powerful than conventional rocket engines.

•Very efficient, good for long-distance Interplanetary space travel missions.

•First developed by Russia during 1963-1965 to propel spacecraft to Mars. Now in
common use!

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