Grade 12 Chemistry: Models of Atoms
This worksheet covers the historical development and key features of atomic models, including Dalton's, Thomson's, Rutherford's, Bohr's, and the Quantum Mechanical Model, suitable for Grade 12 Chemistry students.
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Grade 12 Chemistry: Models of Atoms
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Read each question carefully and answer to the best of your ability. Show all your work for calculations.
1. Which atomic model proposed that electrons orbit the nucleus in fixed energy levels?
Dalton's Model
Thomson's Plum Pudding Model
Bohr's Model
Rutherford's Model
2. The discovery of the electron led to the modification of which atomic model?
Rutherford's Model
Bohr's Model
Dalton's Model
Quantum Mechanical Model
1. In Rutherford's gold foil experiment, most alpha particles passed straight through, indicating that the atom is mostly .
2. The model describes electrons in terms of probabilities of finding them in certain regions around the nucleus called orbitals.
3. J.J. Thomson proposed the model, where electrons are embedded in a sphere of positive charge.
1. Dalton's atomic theory stated that atoms of the same element are identical in mass and properties.
True
False
2. The Bohr model successfully explained the spectra of multi-electron atoms.
True
False
1. Briefly describe the main differences between Rutherford's model and Bohr's model of the atom.
2. Explain why the Quantum Mechanical Model is considered a more accurate representation of the atom than previous models.
Match each scientist with their contribution to atomic theory.
1. John Dalton
a. Discovered the electron
2. J.J. Thomson
b. Proposed the planetary model with a dense nucleus
3. Ernest Rutherford
c. Developed the first atomic theory based on experimental evidence
4. Niels Bohr
d. Proposed electrons orbit in fixed energy levels