What experimental evidence led to the development of this atomic model from the one before it?

To address the question about the development of atomic models, let's focus on the transition from one significant atomic model to another, specifically from the Thomson model to the Rutherford model.

Step 1: Define the Problem

Identify the key components of the question:

• Determine which atomic model is being discussed.
• Identify the experimental evidence that led to the development of the new model.

Step 2: Break Down the Problem

Divide the problem into smaller parts:

• Understand the Thomson atomic model.
• Identify the experiment that challenged this model.
• Understand the Rutherford atomic model and how it differed.

Step 3: Apply Relevant Concepts

• Thomson Model: Known as the "plum pudding model," it suggested that the atom was a sphere of positive charge with negatively charged electrons embedded within it.
• Rutherford Experiment: The gold foil experiment conducted by Ernest Rutherford, Hans Geiger, and Ernest Marsden.
• Rutherford Model: Proposed a nuclear model of the atom with a dense, positively charged nucleus at the center and electrons orbiting around it.

Step 4: Analysis, Verify and Summarize

• Gold Foil Experiment: Rutherford's team directed alpha particles at a thin sheet of gold foil. They observed that most particles passed through, but some were deflected at large angles.
• Analysis: The deflection of alpha particles indicated that a dense, positively charged center (nucleus) existed, which was inconsistent with the Thomson model.
• Verification: The results were repeatable and consistent, leading to the conclusion that the atom has a small, dense nucleus.

Final Answer

The experimental evidence that led to the development of the Rutherford atomic model from the Thomson model was the gold foil experiment. This experiment demonstrated that atoms have a small, dense, positively charged nucleus, which was a significant departure from the "plum pudding" model proposed by Thomson.