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I. Structure of the Atom The Early Models of the Atom.

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Presentation on theme: "I. Structure of the Atom The Early Models of the Atom."— Presentation transcript:

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2 I. Structure of the Atom The Early Models of the Atom

3 Laws n Law of Conservation of Mass n Law of Definite /Constant Proportion- compounds have a ________ composition. Carbon tetrachloride is always 1 atom carbon per 4 atoms chlorine. Carbon tetrachloride is always 1 atom carbon per 4 atoms chlorine. They react in specific ratios by mass. They react in specific ratios by mass. n Law of Multiple Proportions- When two elements form more than ______compound, the ratios of the masses of the second element that combine with one gram of the first can be ______ to small whole numbers. The ratio of the masses of oxygen in H 2 O and H 2 O 2 will be a small whole number (2). The ratio of the masses of oxygen in H 2 O and H 2 O 2 will be a small whole number (2).

4 Daltons Atomic Theory 1) Elements are made up of _________ 2) Atoms of each element are _______. Atoms of different elements are different. 3) Compounds are formed when atoms combine. Each compound has a specific _______ and ______ of atom. 4) Chemical reactions are ________ of atoms. Atoms are not _____ or destroyed.

5 Plum Pudding Model n J.J. Thomson is credited with the discovery of the electron _______ Experimentation e-/m ratio _______ Experimentatione- Charge

6 Thomsons Experiment Voltage source +-

7 Thomsons Experiment Voltage source +-

8 n Passing an electric current makes a beam appear to move from the _____ to the _____ end. Thomsons Experiment Voltage source +-

9 Thomsons Experiment n By adding an electric field

10 Voltage source Thomsons Experiment n By adding an electric field, he found that the moving pieces were __________ + -

11 Thomsons Model n Found the electron. n Couldnt find positive (for a while). n Said the atom was like n A bunch of positive stuff, with the ______ able to be removed.

12 Millikans Experiment Oil Atomizer Oil droplets Telescope - +

13 Millikans Experiment X-rays _______ give some electrons a charge.

14 Millikans Experiment Some drops would hover From the m of the drop and the charge on the plates, he calculated the ___________

15 Rutherfords Experiment n Used to produce alpha particles (+ charged particles). n Aimed alpha particles at gold foil by drilling hole in block. n Since the mass is evenly distributed in gold atoms alpha particles should go through. n Used gold foil because it could be made atoms thin.

16 Lead block Uranium Gold Foil Florescent Screen

17 What he expected

18 Because

19 Because, he thought the mass was evenly distributed in the atom.

20 What he got

21 How he explained it + n Atom is mostly _____ n Small dense, _______ piece at center. n Alpha particles are ______ by n it if they get close enough.

22 +

23 Modern View n The atom is mostly empty space. n regions n Nucleus- protons and neutrons. n Electron cloud- region where you might find an

24 The Mass and Change of the Electron, Proton, and Neutron

25 Sub-atomic Particles n ___- atomic number = number of protons determines type of atom. n ___ - mass number = number of protons + neutrons. n __________ = number of electrons if neutral.

26 Symbols X A Z Na 23 11

27 Niels Bohr Atomic Model Fixed Orbits, Predictable Paths Derived from Max Plancks description of light packets or quanta called photons

28 THE QUANTUM MECHANICAL MODEL 1924-Louis DeBroglie applied ____________to model 1927-Erwin Schrodinger applied wave equation to model Heinsbergs Principle said speed and position cannot be calculated at same time

29 TOO MUCH BRAINPOWER IN ONE PLACE The Atomic Theorists


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