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Atoms: Development of the Atomic Theory. ATOMIC STRUCTURE. S.MORRIS 2006. Who are these men?. In this lesson, we’ll learn about the men whose quests for knowledge about the fundamental nature of the universe helped define our views. Democritus.
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ATOMIC STRUCTURE S.MORRIS 2006
Who are these men? In this lesson, we’ll learn about the men whose quests for knowledge about the fundamental nature of the universe helped define our views.
Democritus • 460 BC - Greek philosopher proposes the existence of the atom • He pounded materials until he made them into smaller and smaller parts • He called them atoma which is Greek for “indivisible”.
Democritus • His Theory: All atoms: • Are small hard particles • Are made of a single material formed into different shapes and sizes • Are always moving, and they form different materials by joining together
John Dalton • 1803 - British chemist; elements combine in specific proportions to form compounds Solid Sphere Model or Bowling Ball Model Proposed by John Dalton
John Dalton • His Theory: • All substances are made of atoms that cannot be created, divided, or destroyed. • Atoms join with other atoms to make new substances. • Atoms of the same element are exactly alike, and • atoms of different elements are different in mass and size.
J.J. Thomson • 1897 - English chemist and physicist; discovered 1st subatomic particles Plum Pudding Model or Raisin Bun Model Proposed by J.J. Thomson
J.J. Thomson • His Theory: • Atoms contain negatively charged particles called electronsandpositively charged matter. • Created a model to describe the atom as a sphere filled with positive matter with negative particles mixed in • Referred to it as the plum pudding model
Ernest Rutherford • 1912 - New Zealand physicist discovered the nucleus Nuclear Model Proposed by Ernest Rutherford
Ernest Rutherford • His Theory: • Small, dense, positively charged particle present in nucleus called a proton • Electronstravel around the nucleus,but their exact places cannot be described. gold foil gold foil helium nuclei helium nuclei
Niels Bohr • 1913 - Danish physicist; discovered energy levels Bohr Model or Planetary Model Proposed by Niels Bohr
Niels Bohr • His Theory: • Electrons travel around the nucleus in definite paths and fixed distances. • Electrons can jump from one level to a path in another level.
Erwin Shrodinger • 1924 - Austrian physicist; developed the electron cloud model Electron Cloud Model Proposed by Erwin Schrodinger
Erwin Shrodinger • His Theory: • The exact path of electrons cannot be predicted. • The region referred to as the electron cloud, is an area where electrons can likely be found.
James Chadwick • 1932 - English physicist; discovered neutrons • His Theory: • Neutrons have no electrical charge. • Neutrons have a mass nearly equal to the mass of a proton. • Unit of measurement for subatomic particles is the atomic mass unit (amu).
Levels of OrganizationParts of Matter smallest largest
Now if you a real ‘G’, as in GENIUS…… What you know about this??? Which element is it?
Modern Theory of the Atom Atomsare composed of three main subatomicparticles: the electron, proton, and neutron. Most of the mass of the atom is concentrated in the nucleus of the atom.