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Unit 5 Changes in the Atomic Model

Unit 5 Changes in the Atomic Model. Democritus (460 - 370BC). Theory: Named “ atomos ” meaning indivisible All things are composed of invisible, indestructible particles of pure matter. Atoms move forever in empty space Atoms are made of the same matter

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Unit 5 Changes in the Atomic Model

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  1. Unit 5Changes in the Atomic Model

  2. Democritus (460 - 370BC) • Theory: Named “atomos”meaning indivisible • All things are composed of invisible, indestructible particles of pure matter. • Atoms move forever in empty space • Atoms are made of the same matter yet differ in shape, size, weight,and position • Drawing – Atomos; Particles & Electrons - NC

  3. Aristotle 4 BC • Did not think atoms existed • Believed everything was uniform • Example: Birds and Bats both fly so they are of the same species • Not on chart*

  4. John Dalton (1766 - 1844) • Theory: Atoms are small, solid, spherical objects. • Each different kind of element is represented by a different kind of atom. • Each different kind of atom has its own distinct mass. • Atoms are indivisible. • Particles – Sphere & Electrons - NC Drawing

  5. Sir Joseph John Thomson (1856 - 1940) Drawing – 1st particles • Theory: Based on the evidence, came up with his "Plum Pudding" or the “Chocolate Chip Cookie” model of the atom

  6. Particles: Atoms are composed of smaller particles or negative electrons (-) in a positive sphere. These particles are the same for all different types of atoms. Electrons - Electrons are evenly spread out within a positive sphere to make up a neutral atom.

  7. Ernest Rutherford (1871 - 1937) • Theory:Based on the Gold Foil Experiment • Particles: Atoms have a positive nucleus (+), that contains most of the mass of the atom. The electrons(-) are in the empty space.

  8. Drawing – 1st nucleus Electrons: The electrons (-) are in the empty space surrounding the positive nucleus.

  9. Niels Bohr (1885 - 1962) • Theory: Electrons move in orbits or certain paths. • Particles: Nucleus contains positive protons (+) and neutral neutrons (0). Electrons (-) are in orbits. Drawing – 1st neutrons

  10. Electrons:travel in within fixed orbits or energy levels surrounding the nucleus. • The only way for an electron to change its energy level is for it to instantaneously change orbits.

  11. Bohr (1885 - 1962) Theory lead to the idea that electrons exist in shells Electrons in the outermost shell determine an atom's chemical properties

  12. Electron Cloud or Quantum Model (1926) • Theory: it is impossible to know the exact position and momentum of an electron. • Protons and Neutrons have smaller particles called quarks. Drawing – 1st quarks

  13. Electron Cloud Model (1926) • Particles: Electrons (-), Protons (+), Neutrons (0), and quarks • Electrons:The electrons are in the cloud surrounding the nucleus. The cloud is 100,000 times larger than size of nucleus. • Electrons do not travel in distinct orbits, rather like rotating blades of a ceiling fan.

  14. Label each atom model

  15. A baseball stadium size atom!If an atom had a diameter of 500 feet, about the size of a large stadium, then its nucleus would be about as big as the tiny ball in the referees whistle! Imagine a speck of dust floating around the stadium that is an electron!

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