Major subatomic Particles

• Atoms are measured in picometers (10^-12) meters
• Radius of nucleus is on the order of 10^-15m
• Density w/in atoms i near 10^14 g/cm3

Voice Notes:

• Isotopes that aren’t included in periodic tables are radioisotopes
• The further you go away, the more reactive (for metals)
• Bohr heated up hydrogen and helium and used math to explain his theory
  • Used the amnt of energy given off after being heated (observed the photons released)
  • Used the line spectrum
• Reviewed visible light spectrum

Bohr’s Model

Why don’t electrons fall into the nucleus?

• Move like planets around the sun
• In circular orbits at different levels
• Amounts of energy separate one level from another

Bohr postulated that:

• Fixed energy related to the orbit
• Electrons cannot exist between orbits
• The higher the energy level, the further it is away from the nucleus
• An atom with maximum number of electrons in the outermost orbital energy level is stable (unreactive)

How did he develop his theory?

He used math to explain the visible spectrum of hydrogen gas

Bohr’s Triumph

His theory heled to explain periodic law

Halogens are so reactive because it has one e- less than a full outer orbital

Alkali metals are also reactive because they have only one e- in outer orbital

Drawback

Bohr’s theory didn’t show the shape or the path traveled by electrons

His theory only explained hydrogen and not the more complex atoms

TEXTBOOK READINGS Pg. 174-180