JJ Thompson vs Ernest Rutherford

Which crucial component was a key feature of J.J. Thomson's cathode ray tube experiment that allowed him to deflect the cathode rays?

• A fluorescent screen to detect the rays.

• A vacuum pump to remove air from the tube.

• Electrically charged plates and magnets.

• A thin gold foil target.

What was the most unexpected observation made by Ernest Rutherford and his team during the gold foil experiment?

• Most alpha particles passed straight through the gold foil.

• Some alpha particles were slightly deflected at small angles.

• A small fraction of alpha particles were deflected at large angles, some even back towards the source.

• The gold foil emitted visible light when bombarded with alpha particles.

Thomson's plum pudding model proposed that the atom consisted of:

• A dense, positively charged nucleus surrounded by electrons.

• Negatively charged electrons embedded within a uniformly distributed positive charge.

• Neutral neutrons at the center, orbited by protons and electrons.

• Positively charged protons concentrated in a small nucleus.

Rutherford's nuclear model of the atom differed most significantly from Thomson's model in its description of:

• The presence of negatively charged particles.

• The overall electrical neutrality of the atom.

• The distribution of positive charge within the atom.

• The existence of empty space within the atom.

A student claims that Thomson's experiment directly proved the existence of a dense, positively charged nucleus. Evaluate this claim.

• The claim is correct; the deflection of cathode rays indicated a concentrated positive charge.

• The claim is incorrect; Thomson's experiment demonstrated the existence of negatively charged particles.

• The claim is partially correct; while Thomson found charged particles, he didn't determine the nucleus.

• The claim is irrelevant; Thomson's experiment focused on the overall neutrality of the atom.

What was a significant limitation of Thomson's plum pudding model that Rutherford's gold foil experiment directly addressed and ultimately refuted?

• Its inability to explain the existence of isotopes.

• Its lack of a mechanism for chemical bonding.

• Its depiction of a diffuse positive charge that could not cause large deflections of alpha particles.

• Its failure to account for the photoelectric effect.

Consider two hypothetical experiments: Experiment X involves firing neutral particles at a thin metal foil, and Experiment Y involves firing positively charged particles at the same foil. Based on Rutherford's findings, which experiment would be more likely to show significant deflections of the incident particles?

• Experiment X, because neutral particles are more easily influenced by the atom's overall charge.

• Experiment Y, because the positively charged particles would be repelled by the concentrated positive charge of the nucleus.

• Both experiments would show similar levels of deflection, as mass is the primary factor.

• Neither experiment would show significant deflection, as atoms are mostly empty space.

How did Rutherford's conclusions about the atom fundamentally change the scientific understanding of matter compared to the prevailing view before his work?

• It introduced the concept of electrons as fundamental particles.

• It established the idea that atoms are indivisible and solid spheres.

• It proposed that the atom has a dense, positively charged nucleus and is mostly empty space.

• It suggested that atoms are constantly undergoing radioactive decay.

Which statement best summarizes the progression of atomic theory from Thomson to Rutherford?

• Thomson discovered the nucleus, and Rutherford determined the existence of electrons.

• Thomson proposed a solid, indivisible atom, while Rutherford introduced the idea of electron orbits.

• Thomson's model featured a diffuse positive charge with embedded electrons, while Rutherford's model proposed a concentrated positive charge at the center.

• Rutherford's experiment confirmed Thomson's plum pudding model with more precise measurements.

If the alpha particles had more kinetic energy would they be deflected at higher or smaller angles?'

• The alpha particles would be deflected at smaller angles because repulsion by the nuclei would have less time to act on the alpha particle

• The results would be identical, as the kinetic energy of the alpha particles does not affect their interaction with the atomic nucleus.

• Fewer alpha particles would be deflected, suggesting a weaker nuclear charge.

• More alpha particles would pass straight through, indicating a smaller nucleus.