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Atomic Theory

Atomic Theory. The Movers and Shakers of the Subatomic World. Dalton. In the early 1800’s, the English chemist John Dalton did a number of experiments that eventually led to the acceptance of the idea of atoms . Dalton’s Atomic Theory.

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Atomic Theory

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  1. Atomic Theory The Movers and Shakers of the Subatomic World.

  2. Dalton • In the early 1800’s, the English chemist John Dalton did a number of experiments that eventually led to the acceptance of the idea of atoms.

  3. Dalton’s Atomic Theory • All elements are composed of atoms. Atoms are invisible and indestructible particles.

  4. continued... • Atoms of the same element are exactly alike. H H

  5. continued... • Atoms of differentelements are different. O H

  6. continued... • Compounds are formed by the joining of atoms of two or more elements. H H O

  7. Questions... • What were the four parts of the Dalton’s atomic theory? • Say it again...

  8. Was he right? • Dalton’s atomic theory of matter became one of the foundations of chemistry. • BUT it needed work…other scientists had to modify the theory.

  9. Thomson • In 1897, the work of an English scientist J. J. Thompson provided the first hint that atoms were made up of even smaller particles • Atoms are divisible…Dalton was wrong!

  10. Thompson’s Model • He stated that atoms are made up of positively (+) and negatively (-) charged particles

  11. And... • He thought the positive(+) and negative (-) particles were s p r e a d o u t in atoms likep p u l d u d m i s n • (plums inpuddin’)

  12. Questions... • What kind of particles did Thompson find in atoms? • What did his idea of an atom look like?

  13. Was Thomson Right? • Not really…there arepositively(+) and negatively (-) charged particles inside atoms. • BUT...

  14. Rutherford’s Model • In 1908, Rutherford discovered the nucleus. • He stated that atoms have a small, dense, positively (+) charged center called a nucleus.

  15. Questions... • What did Rutherford find inside the atom? • What did Rutherford’s atom look like?

  16. So... • Particles are not spread out like plums in pudding… • Positive particles (protons) are in the center (nucleus). • Where are the negative particles (electrons)?

  17. Bohr’s Model • In 1913, Niels Bohr proposed an improvement to Rutherford’s Model: • Electron’s move in definite orbits around the nucleus, like planets around the sun.

  18. Questions... • What did Bohr propose? • Where were the particles in Bohr’s model of an atom? • What did it look like? • What was special about the electrons in Bohr’s model?

  19. Are we there yet? • Bohr’smodel was used for a long time… • BUT...

  20. Modern Atomic Model • An atom has a small,positively charged nucleus surrounded by a large region in which there are enough electrons (-) to make the atom neutral (0).

  21. E E E E E P P P E P P P P P P P P P E E E E E E

  22. Questions... • Do electrons have specific orbits in the modern model? • What does the atom look like in the new model?

  23. Make Your Timeline • After the sheet is passed out: • write your name on it! • Fill out the timeline according to date, scientist, notes, and picture (if there is one) for each scientist we went over. • Neatness counts!!!!! • HAVE FUN

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