Scientists

• Who developed the idea of atomic nature


  John Dalton
• Atoms have negative and poitive parts 


  J.J Thomson
• J.J Thomason discovered what negatiely charged particle 


  electrons
• revived the atomic theory


  John Dalton
• model of atom has been called "billiard ball" model 


  John Dalton
• Law of Constant Composition in his theory

  John Dalton
• All matter consists of tiny particles and atoms are indestructible and unchangable


  John Dalton
• the atom is a positively charged spherical bodyin which

  tiny negatively charged electrons are embedded.


  J.J Thomson
• Blueberry muffin model


  J.J Thomson
• Concluded that the positive charge in an atom is concentrated in a very small volume of the atom

  Ernest Rutherford
• atoms were made up of mostly empty space.

  Ernest Rutherford
• gold foil theory


  Ernest Rutherford
• atom is equal number of negatively charged electrons and

  positively charged protons.

  Ernest Rutherford
• Most of the mass of the atom and all of its positive charge is contained in a tiny core region called the nucleus.


  Ernest Rutherford
• Electrons circle the nucleus along defined paths called orbits


  Ernest Rutherford
• Light can be decribed as a wave


  Christian Huggens
• Light consisted of tiny particles


  Christian Huggens
• Described light as electromagnetic wave

  James Maxwell
• Continuous range of electromagnetic radiation exists

  James Maxwell
• Each wavelength of radiation is characterized by its own frequency & wavelength.

  James Maxwell
• Discovered the photoelectric effect by accident

  Heinrich
• The energy associated with emitted electrons is not related to the

  intensity of the light, but instead is a function of the frequency of

  coloured light.

  Heinrich Hertz
• Discovered that blackbodies would radiate different colours of light depending on their temperature and helped to invent the electroscope


  Gustav Kirchhoff
• minimum energy packet is called a quantum


  Max Planck
• stated that energies of atoms in a heated solid were not continuous, but rather multiples of a smaller amount of energy

  Max Planck
• Light energy consists of pulsating bursts of energy called quanta or photons


  Albert Einstein
• Used the concept of light consisting of quanta of energy to explain the photoelectric effect

  Albert Einstein
• Hypothesized that electrons behaved as standing waves around the necleus of an atom

  Louis de broglie
• Because of their constant motion and electrostatic repulsion electrons do not move in simple, defined orbits as Bohr suggested


  Louis de broglie
• you could measure the position ot an electron (or other particle) OR you could

  measure its momentum

  Werner Heisenberg
• Stated that there are limits to our ability to know both the location and the speed of electrons 


  Werner Heisenberg
• wave-mechanical equation because it treats the electron as both a

  wave and a particle.

  Erwin Schrodinger
• electrons contined in their orbits would set up standing

  waves and you could describe only the probability of where an electron could be.

  Erwin Schrodinger
• concluded that electron behaviour cannot be exactly described, but only discussed as a wave mechanical question

  Erwin Schrodinger
• concluded that electrons travel in circular orbits in the atom with quantized energy

  niels bohr
• electrons are found orbiting the nucleus in fixed, discrete (energy) levels


  niels bohr
• each quantum level is further from the nucleus and greater energy level


  niels bohr
• discovered the neutron

  james chadwick
• Different number of neutrons are called isotopes

  James Chadwick
• Studied matter in cathode ray rubes

  Chadwick and Thomson