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Flashcards in Quantum Deck (15)
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1
Q

What is Thomson’s Plum pudding model?

A

The atom is a positively charged fluid with symmetrically placed electrons

2
Q

What is Rutherford’s Model Experiment?

A

Alpha particles were directed onto gold foil which could allow the particles to penetrate the sheet and be recorded on a screen.

3
Q

What were the findings of Rutherford’s Experiment?

A
  • most particles passed with little to no deflection
  • some were scattered through small but significant angles
  • very small # were deflected at very large angles

These findings could not be explained by Thompson’s model.

4
Q

What was Rutherford’s model?

A

The atom consists of a small, massive positively charged core (nucleus) surrounded by revolving electrons.

5
Q

What are the limitations of the Rutherford model?

A
  • cannot explain why electrons didn’t accelerate towards nucleus
  • cannot explain why the nucleus didn’t disintergrate
  • cannot explain what made up the nucleus to make it positive
6
Q

What is the Bohr’s Model?

A

States:

  • electrons are restricted to move in certain selected orbits of definite energy levels (in these states electrons do not radiate energy)
  • energy is emitted and absorbed by atoms in discrete quanta (energy packets)
  • emission of radiation by an electron would be by quantum jumps from one fixed state to another
7
Q

What are the limitations of Bohr’s model?

A
  • cannot explain the Zeeman effect (the splitting of a spectral line into hyperfine lines when placed in a very strong magnetic field)
  • can only be used to describe atoms/ions with 1 electron in the 1st energy level (e.g. Hydrogen)
  • cannot explain relative intensity of spectral limes
8
Q

What are photons?

A

Discrete units of energy representing the smallest quantity of light at that frequency.

9
Q

What occurs during alpha decay?

A

An alpha particle is released and the reactant changes element

10
Q

Why does alpha decay occur?

A

If the atom is too big, the atomic number is greater than 83

11
Q

What occurs during beta - decay?

A

A neutron turns into a proton, an electron and an antineutrino

12
Q

What occurs during beta + decay?

A

A proton turns into a neutron, a positron and a neutrino

13
Q

What occurs during fission?

A

A large nucleus splits into two nuclei with smaller mass numbers and usually a neutron is released.

14
Q

What occurs during fusion?

A

2 nuclei combine to form a nucleus of a lighter mass number.

15
Q

What happens in the Frank Hertz Experiment?

A
  • cathode is heated and releases electrons (thermionic emission)
  • the electrons are attracted to the mess grid and if they have enough energy they will hit the collecting plate
  • when the 1st energy level voltage(e.g. 4.9eV) is applied, the electrons released form the cathode have enough energy to change the energy level of the electrons from the gas
  • the energy of the cathode electrons is lowered from these collisions and less of these electrons hit the collecting plate. Therefore the current decreases.