Chapter 17 Flashcards
Before Rutherford’s experiment, what was the widely accepted model of the atom?
That the atom was a positively charged globule with negatively charged electrons sprinkled in it.
What conclusions did Rutherford’s experiment lead to?
- Most of the fast, charged alpha particles went through the gold foil. Hence, the atom is mostly empty space.
- Some of the alpha particles deflected back through significant angles. Therefore, the centre of the atom must be tiny but contain a lot of mass.
- Alpha particles were repelled so the nucleus must have a positive charge.
- Atoms are neutral overall so electrons must exist outside of the nucleus.
When does an alpha particle bounce back?
At the point where EPE = INITIAL KE
What are hadrons?
Particles that feel the strong interaction force.
Made of quarks
What are the two types of hadrons?
Baryons (3 quarks) and Mesons (2 quarks)
What are baryons?
- Hadrons
2. Protons and neutrons
What do all baryons decay to?
Protons (except from protons)
What are leptons?
Fundamental particles that don’t feel the strong interaction.
Interact through weak interactions
What is an antiparticle?
Identical particles of equal mass with opposite charge and opposite lepton or baryon number.
What is annihilation?
When a particle and its antiparticle collide, all the mass is converted into energy. The result is 2 photons.
Wavelength of an electron (De Broglie)
Lambda = h/p = hc/E
What do different energy levels in an atom correspond to?
Different standing waves
Composition of a proton
2 up quarks, 1 down quark
Composition of a neutron
2 down quarks, 1 up quark.
How do electrons move down an energy level?
By emitting a photon
