Video Transcript
Which of the following is not true about the gold leaf experiment? (A) A very small number of particles were significantly reflected backward. (B) Most positively charged 𝛼 particles passed through the foil without being deflected. (C) The 𝛼 particles used consisted of two protons and two neutrons. (D) Most positively charged 𝛽 particles passed through the foil without being deflected. Or (E) some 𝛼 particles were slightly deflected.
The gold leaf experiment, also called the gold foil experiment, was one of the most groundbreaking experiments that furthered our understanding of atomic structure. The experiment was designed by scientist Ernest Rutherford. The experiment used a radium source to produce a beam of 𝛼 particles which were aimed at a thin gold leaf. A detection screen was placed around the gold foil. The experiment’s aim was to determine how the 𝛼 particles would interact with the atoms in the gold foil. The alpha particles emitted by the radium source each consisted of two protons and two neutrons giving them an overall positive charge.
Since the question is asking us to determine which statement is not true, using this information about 𝛼 particles, we can eliminate answer choice (C). When these 𝛼 particles were fired at the gold leaf, the detection screen revealed that most of the 𝛼 particles passed straight through the foil and were not noticeably affected by the gold leaf. Therefore, we can eliminate answer choice (B). This result suggested that atoms contain large amounts of empty space.
However, this was not the only behavior the 𝛼 particles exhibited. The 𝛼 particles were scattered to varying degrees. Many of the 𝛼 particles were deflected at small angles, and very few were reflected backward. These results suggested that atoms have a positively charged center or nucleus. Using this information, we can also eliminate answer choices (A) and (E). It was 𝛼 particles not 𝛽 particles that led to this important discovery. Therefore, the statement that is not true about the gold leaf experiment is answer choice (D), most positively charged 𝛽 particles passed through the foil without being deflected.
