Discovery of the Atom

J.J. Thomson is credited with the discovery of the first subatomic particle, the electron. To make his discovery, Thomson conducted several experiments with cathode ray tubes and analyzed the bright beam that went across the tube. Which of the following is not an accurate conclusion that Thomson drew from his experiment?

• The beam was made of particles because it was bent by a simple magnet

• The beam was negatively charge since it was attracted to a positive charged.

• The beam was much smaller than hydrogen based on the mass to charge ratio.

• The beam was emitted from the nucleus of atoms because light was given off.

Ernest Rutherford is credited with the discovery of the nucleus of atoms. Which of the following

experimental setups was used by Rutherford to make this momentous discovery?

• A thin sheet of gold was bombarded with alpha particles and deflections were detected on a sheet of zinc sulfide.

• The beam within a Crookes tube was observed using fluorescent material and the behavior of the beam in electromagnetic fields was examined

• The light emitted from fluorescent materials was analyzed to determine the energy that was contained within each photon.

• The atomic weights and chemical properties of similar atoms were analyzed and recorded until patterns emerged

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Niels Bohr was a great contributor to our understanding of the atomic model. Which of the following conclusions that was drawn by Bohr remains in our current model of the atom?

• Electrons circle the nucleus of the atom in fixed orbits

• Electrons are contained within different energy levels in the atom

• The nucleus contains both protons and neutrons

• Electrons are negatively charged particles which are much smaller than protons

Which of these conclusions can be drawn from Rutherford's experiment?

• Each atom contains electrons.

• The nucleus of an atom can be split.

• Each atom contains protons.

• Atoms are mostly empty space

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Which scientist was the first to conclude through experimentation that atoms have positive charges in their nuclei?

• Bohr

• Dalton

• Mosely

• Rutherford

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After 1911, most scientists accepted the theory that the nucleus of an atom was very dense and very

small and had a positive charge. What led scientists to accept this theory?

• Dalton's theory of the atom was over 100 years old.

• Scientists before 1911 used the scientific method of inquiry improperly

• A new model proved that the quantum theory of the atom was inaccurate.

• Rutherford did an experiment firing alpha particles at a thin piece of gold foil.