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Structure of the Atom PSC Ch. 3-2
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The Atom Subatomic particles The nucleus
The notation and the periodic table Isotopes and Ions Determining atomic mass
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Subatomic Particles Electrons Discovered by J.J. Thompson
Discovered how: Cathode ray tubes-rays traveled from cathode to anode, bent by electric and/or magnetic field, caused paddle wheel to turn Vital Stats… Mass: 9 X kg , ~1/2000 mass of p+, u Charge: -1, -1.30x10-19c, Location: electron cloud / outside nucleus
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Subatomic Particles Protons Discovered by J.J. Thompson
Discovered how: Modified cathode ray tube particles traveled from anode to cathode Vital Stats: Mass: X kg; ~2000x mass of e-, 1.007u Charge: +1, 1.60x10-19c Location: nucleus
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Subatomic Particles Neutrons Discovered by James Chadwick
Discovered how: High energy beam unaffected by magnetic or electric fields Vital Stats: Mass: X kg (very similar to the proton) Charge: 0, neutral Location: in the nucleus
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The Nucleus Discovered by Lord Ernest Rutherford Discovered how :
Gold foil experiment- + charged particles shot at thin gold foil. Most went straight through, some deflected. Very few bounced straight back Small dense + charged core in atom (atom is mostly empty space) Vital Stats: + charge Dense – over 99% of the atom’s mass 1/trillionth the volume of the atom
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Graphic Organizer ATOM e- cloud Nucleus -Most of volume -99% of mass
-Very little mass Nucleus -99% of mass -1/trillionth of volume e - (electrons) -.0005u -neg charge, -1 -J.J. Thompson -cathode ray tube p+ (protons) -modified cathode ray tube -positive charge, +1 -1.007u no (neutrons) -James Chadwick -no charge -1.009u
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Isotopes Sometimes atoms of the same elements have a different number of neutrons All elements have isotopes! And they exist in different abundances.
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Ions (p. 161) Sometimes atoms will gain or lose electrons
Too many : negative charge Too few: positive charge
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