Conversion of one nucleus into another was first demonstrated in 1919 by __________.
First, I need to recall who first demonstrated nuclear transmutation. The key here is the year 1919. I remember that Ernest Rutherford did some work in nuclear physics. Wait, wasn't it Rutherford who discovered the nucleus? But the question is about converting one nucleus into another. Let me think. Yes, Rutherford conducted experiments around that time. In 1919, he bombarded nitrogen with alpha particles and observed the emission of protons, which led to the conversion of nitrogen into oxygen. That was the first artificial transmutation. So the correct answer should be Ernest Rutherford.
Now, the core concept here is nuclear transmutation, specifically the first demonstration by Rutherford. The mechanism involves alpha particle bombardment causing a nuclear reaction. The correct answer is Rutherford because his experiment in 1919 was pivotal. The other options would be incorrect if they are other scientists, like Becquerel, Curie, or others. For example, Becquerel discovered radioactivity, which is different. Marie Curie worked on radioactivity but not transmutation. Einstein's mass-energy equivalence is related but not the direct answer here. The clinical pearl is to remember Rutherford's experiment as the first artificial transmutation. Need to make sure the explanation is concise and fits the character limit. Let me structure each section with the required parts, keeping it within 2500 characters. Check each section for accuracy and correct terminology.
**Core Concept**
The question pertains to the **first experimental demonstration of nuclear transmutation**, a foundational concept in nuclear physics. In 1919, Ernest Rutherford bombarded nitrogen nuclei with alpha particles, resulting in the conversion of nitrogen to oxygen through proton emission—a pivotal milestone in understanding atomic structure and nuclear reactions.
**Why the Correct Answer is Right**
**Ernest Rutherford** conducted the experiment where alpha particles (helium nuclei) collided with nitrogen nuclei, inducing the reaction:
**¹⁴N + α → ¹⁷O + p**. This demonstrated that one element (nitrogen) could be artificially transformed into another (oxygen) via nuclear reactions. Rutherford’s work established the basis for nuclear physics and later advancements in particle physics. The experiment utilized a radioactive source (radium) to generate alpha particles, marking the first human-induced nuclear reaction.
**Why Each Wrong Option is Incorrect**
**Option A:** *Marie Curie* pioneered research on radioactivity but did not demonstrate nuclear transmutation.
**Option B:** *James Chadwick* discovered the neutron in 1932, unrelated to 1919 transmutation.
**Option C:** *Niels Bohr* developed the atomic model but did not perform nuclear transmutation experiments.
**Clinical Pearl / High-Yield Fact**
Remember: **Rutherford’s 1919 experiment** is the **first artificial nuclear transmutation**. Use the acronym **RADIATE**: *Rutherford Achieved Discovery In Alpha Transmutation Experiment*. This is a classic exam trap where candidates confuse radioactivity (Curie/Becquerel) with nuclear reactions (R