Download - Discovery of the Electron, Models & Theories
Discovery of the Electron, Models &
Theories
JeffreyThorinDaniel
JJ Thompson• Discovered the
electron• Wrote books on
atomic theory and structure
• First to suggest that atoms have parts
Robert Millikan• Found the accurate
way to decide the charge carried with an atom
Niels Bohr Louis de Broglie
• Helped create a picture of the atomic structure(Bohr model)
• This said that electrons orbit the nucleus in fixed circular orbits
• Looked into Bohr’s investigation and thought electrons moved in waves rather that circular orbits
Werner Heisenberg Erwin Schrodinger
• Known for his theory in quantum mechanics
• Proved Bohr’s theory wrong about the movement of electrons
• Said we can’t assign to an electron a position in space at a given time, nor follow it in its orbit
• Developed a wave-equation that accurately gave energy levels to atoms
Bohr Model An atom consisting of small positively charged nucleus orbited by
negatively charged electrons
Similar to planetary model where planets orbit the Sun
Solar system uses gravitational forces whereas an atom uses electrostatic forces
Electrons have certain orbits with certain radii
Orbits are circular according to quantized energy levels
Orbits with larger radii have larger energies
Quantum ModelBased on quantum theory, which says matter
also has properties associated with waves Impossible to know the exact position and
momentum of an electron at the same timeUses complex shapes of orbitals (electron
clouds) volumes of space in which there is likely to be an electron
Based on probability rather than certainty
Experiments Thompson experimented with cathode rays and magnets that led
to the discovery of the electron
Millikan devised an oil-drop experiment where he’d drop tiny charged droplets to find out their specific charge
Bohr based his model on experiments done by Ernest Rutherford; he saw Rutherford’s model wasn’t quite right and changed it
Broglie saw that Bohr’s model, specifically the electrons, move in waves, not in a circular orbit
Heisenberg also went off of Bohr’s model and elaborated more into quantum mechanics to explain the wave motion of electrons instead of a circular orbit
Schrodinger used mathematical equations to predict the likelihood of finding the electron and eventually found one that worked
Time Line of HistoryScientists from the early 1900sTheories developed without use of more precise
modern technology
Quantum Model
Over time…Bohr’s model had a lot of problems and
inaccuracies to itQuantum model is considered “standard” and is
also considered the most accurate physical theory ever created