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Hmwk. Q..1-7 page 3 (handout)

1. Theory- ability to explain and predict

2.  no…. it can be changed, altered, corrected, improved upon

3.  Law of Conservation of Matter – The mass of the atoms in the reactants equaled the mass of the atoms in the products… only the atoms rearranged themselves in new molecules (compounds).

4.  Dalton

☺The compounds broke down in the same way every time… there were definite proportions of the elements in them.

Different compounds with the same elements in them could be shown to have multiple proportions.

X  - Could not account for the electrical nature of the atom caused by subatomic particles


☺The mass of the atom due mostly to the protons

X – the charge was not uniformly distributed


☺ Protons and neutrons found in the nucleus (dense centre)

atom was mostly space

X – Couldn’t explain the motions of the particles(orbits) and couldn’t understand why the atom didn’t collapse


☺ Correctly explained the spectrum (bright lines) coming off of Hydrogen when it is supplied with energy.  Showed that the electron must occupy certain energy levels.

X – Did not explain the multiple electron systems.



Quantum Mechanical Model

The electron really acts more like a wave than a particle.  Its position is described by Mathematical Probability Equations.

Neils Bohr (1922)i

Werner Heisenberg (1925)

Linus Pauli


Electron occupies orbitals that are cloud like.  Some spherical, some double-lobe, some more complex.

X – can’t explain “dark matter”, neutrinos , particles smaller than electrons.

Ch.10  Electrons in Atoms

Wave Nature of electron