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History of the Atom Model

History of the Atom Model. Air, earth, fire & water. 450 BC. Democritus (Greek)- World was made of 2 things: Empty space Tiny particles call atoms (Atomus= indivisible). Aristotle (Greek)- Matter is continuous and not made of smaller particles.

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History of the Atom Model

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  1. History of the Atom Model Air, earth, fire & water 450 BC • Democritus (Greek)- • World was made of 2 things: • Empty space • Tiny particles call atoms • (Atomus= indivisible) Aristotle (Greek)- Matter is continuous and not made of smaller particles PROBLEM: Neither had any evidence.

  2. 1782 History of the Atom Model Law of Conservation of Matter (mass) Matter is neither created Nor destroyed, it is only rearranged. Antonine Lavoisier (French)- Mass of reactants = Mass of products

  3. 1799 History of the Atom Model Law of Definite Proportions Atoms must combine in whole number ratios. Joseph Proust (French)- H20 vs H0 ½

  4. Joseph Proust (French)- History of the Atom Model 1799 Law of Multiple Proportions Atoms can combine in different whole number ratios. H20 vs H202

  5. Modern Atomic Theory (MAT) Developing 1803 John Dalton (English)- “Father of Modern Atomic Theory” Started teaching at 12 years old.

  6. Dalton’s Atomic Theory • All matter is made up of atoms. Atoms are the smallest fundamental units of matter.

  7. Dalton’s Atomic Theory TRUE • All matter is made up of atoms. Atoms are the smallest fundamental units of matter.

  8. Dalton’s Atomic Theory TRUE • All matter is made up of atoms. Atoms are the smallest fundamental units of matter. • All elements consist of atoms which are indivisible & indestructible.

  9. Dalton’s Atomic Theory TRUE • All matter is made up of atoms. Atoms are the smallest fundamental units of matter. • All elements consist of atoms which are indivisible & indestructible. FALSE Nuclear reactions

  10. Dalton’s Atomic Theory TRUE • All matter is made up of atoms. Atoms are the smallest fundamental units of matter. • All elements consist of atoms which are indivisible & indestructible. • All atoms of the same element are identical in size, shape & mass. FALSE Nuclear reactions

  11. Dalton’s Atomic Theory TRUE • All matter is made up of atoms. Atoms are the smallest fundamental units of matter. • All elements consist of atoms which are indivisible & indestructible. • All atoms of the same element are identical in size, shape & mass. FALSE Nuclear reactions FALSE Isotopes

  12. Dalton’s Atomic Theory TRUE • All matter is made up of atoms. Atoms are the smallest fundamental units of matter. • All elements consist of atoms which are indivisible & indestructible. • All atoms of the same element are identical in size, shape & mass. • Atoms of different elements are different in size, shape, & mass. FALSE Nuclear reactions FALSE Isotopes

  13. Dalton’s Atomic Theory TRUE • All matter is made up of atoms. Atoms are the smallest fundamental units of matter. • All elements consist of atoms which are indivisible & indestructible. • All atoms of the same element are identical in size, shape & mass. • Atoms of different elements are different in size, shape, & mass. FALSE Nuclear reactions FALSE Isotopes TRUE

  14. Dalton’s Atomic Theory TRUE • All matter is made up of atoms. Atoms are the smallest fundamental units of matter. • All elements consist of atoms which are indivisible & indestructible. • All atoms of the same element are identical in size, shape & mass. • Atoms of different elements are different in size, shape, & mass. • In a chemical reaction, atoms are rearranged, never created nor destroyed & they combine in whole number ratios. FALSE FALSE TRUE

  15. Dalton’s Atomic Theory TRUE • All matter is made up of atoms. Atoms are the smallest fundamental units of matter. • All elements consist of atoms which are indivisible & indestructible. • All atoms of the same element are identical in size, shape & mass. • Atoms of different elements are different in size, shape, & mass. • In a chemical reaction, atoms are rearranged, never created nor destroyed & they combine in whole number ratios. FALSE FALSE TRUE TRUE

  16. Dalton’s Atomic Model

  17. 1839 Modern Atomic Theory (MAT) Developing Atomic structure might be related to electricity…it might have a charge. Ben Franklin (English)- Michael Faraday (English)- • 2 types of charges • Positive (later proton) • Negative (later electron)

  18. Problem with Dalton’s Atom Model? Lacks subatomic particles…

  19. 1897 Modern Atomic Theory (MAT) Developing Cathode Ray Tube Experiment JJ Thomson (English)- link

  20. Thomson’s Plum-Pudding Model • - + • + + - • + - + - • + - • + • + • + + + + • + • + • + Protons & Electrons Lots of empty space

  21. Problem with Plum-Pudding Model? • - + • + + - • + - + - • + - • + • + • + + + + • + • + • + • - + • +- +- + - +- • + -- +- +-+- • + - +-+ • +-+- +-+ + and - attract

  22. 1909 Modern Atomic Theory (MAT) Developing Gold Foil Experiment Ernest Rutherford (English) link

  23. Modern Atomic Theory (MAT) Developing The Results & The Explanation • Most of positive charges passed through • because the atom is mostly empty space. • Some of the positive charges deflected • because the atom contains some positive • charge. • Some of positive charges deflected straight • back because there is a concentrated area • of positive charge (nucleus).

  24. _ _ _ _ +++ ++++ +++ _ _ _ _ Rutherford’s Atomic Model Nucleus- Contains Protons Electrons surround nucleus Lots of empty space

  25. _ _ _ _ _ _ +++ ++++ +++ _ +++ ++++ +++ _ _ _ _ _ _ _ _ Problem with Rutherford’s Model? + and - attract Why? Why? Why? Don't the electrons get pulled to the center where the protons are?

  26. 1913 Modern Atomic Theory (MAT) Developing Solar System Model- Electrons are like planets that orbit the nucleus Niels Bohr (American)- link

  27. Problem with Solar System Model? Scientists found this model failed for atoms other than Hydrogen because it couldn’t predict the energy levels of electrons in atoms with more than one electron.

  28. 1924 Modern Atomic Theory (MAT) Developing Wave and particle Model- 1926 Werner Heisenberg (German physicist)- Louis de Broglie (French physicist)- Uncertainty Principle

  29. 1926 Modern Atomic Theory (MAT) Developing Charge Cloud Model- Erwin Schrodinger- (Austrian Physicist) • Basic Parts of the Atom Nucleus Electron Cloud link

  30. ATOM COMPOSITION The atom is mostly empty space • protons and neutrons in the nucleus. • the number of electrons is equal to the number of protons. • electrons in space around the nucleus. • extremely small. One teaspoon of water has 3 times as many atoms as the Atlantic Ocean has teaspoons of water.

  31. Nucleus is Very Massive • Protons - Positive Charge • Neutrons - Neutral • Electrons - Negative

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