The atomic model described with a central purple ball (representing the nucleus) surrounded by overlapping concentric black ovals (which likely represent electron orbitals) and small green balls on each oval (representing electrons) suggests a nucleus with electrons arranged in orbits around it.
The correct experimental evidence that led to the development of this atomic model (likely a representation similar to the Bohr model or later quantum mechanical models) is:
A few of the positive particles aimed at a gold foil seemed to bounce back.
This refers to the famous Rutherford gold foil experiment. In this experiment, alpha particles were directed at a thin sheet of gold, and it was observed that some particles were deflected at large angles while a few bounced back. This led to the conclusion that the atom has a small, dense, positively charged nucleus, contradicting the earlier plum pudding model which suggested that positive charge was spread throughout the atom.
The other options, while important in the development of atomic theory, relate more to specific phenomena rather than the structural model of the atom:
- The specific colors of light emitted from heated atoms pertain to energy levels of electrons but don't give direct evidence of the nucleus.
- The combining proportions of elements help understand chemical reactions and molecular formation but do not directly define atomic structure.
- The behavior of cathode rays in magnetic fields relates to the discovery of the electron but does not specifically lead to the model of the nucleus surrounded by orbiting electrons.
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