Video Transcript
Which of the experiments listed
below did not match its given conclusion? (A) The Rutherford experiment was
useful in determining the nuclear charge on the atom. (B) The Rutherford experiment
confirmed the presence of a positively charged nucleus in the center of the
atom. (C) The Rutherford experiment
proved the Thomson plum pudding model of the atom to be essentially correct. (D) Thomson’s work on the electric
discharge tube showed the existence of negatively charged particles called
electrons. Or (E) Millikan’s oil drop
experiment determined the charge of the electron.
The three main scientists behind
the experiments listed are Rutherford, Thomson, and Millikan. All three contributed crucial
conclusions toward atomic theory. Let’s have a look at their major
experiments to identify the correct answer.
Thomson’s work with cathode rays or
electric discharge tubes allowed him to suggest his plum pudding model. Through his work, he concluded that
atoms contain negatively charged subatomic particles called electrons. His model suggested that these
electrons were contained within atoms in an evenly distributed positive charge. Since the question is asking us to
identify the answer choice that does not match the experiment to its conclusion, we
can eliminate answer choice (D), which does describe Thomson’s conclusion.
Armed with the information that
negatively charged subatomic particles exist, Millikan’s work with charged oil
droplets revealed the behavior of these charged particles. This experiment led to the
determination of an electron’s charge, so we can eliminate answer choice (E).
Rutherford’s gold foil experiment
was groundbreaking, and it yielded unexpected results, which eventually led to the
discovery of the positively charged nucleus. By firing positively charged 𝛼
particles at a thin sheet of gold, Rutherford was able to put Thomson’s plum pudding
model to the test. If the positive charge were evenly
spread in the atom, the 𝛼 particles fired at the gold atoms would pass through. However, on a detecting screen, it
was found that many passed through, some were slightly deflected, and some were
significantly deflected. This led to the conclusion that
atoms contain a dense center or a nucleus that is positively charged. So we can eliminate both answer
choices (A) and (B).
Since Rutherford’s gold foil
experiment essentially proved Thomson’s model to be incorrect, the answer choice
that lists an experiment that does not match its conclusion is answer choice
(C). The Rutherford experiment proved
the Thomson plum pudding model of the atom to be essentially correct.
