Problem 36 - 43 Years JEE ADVANCED (1978-2020) + JEE MAIN Chapterwise & Topicwise Solved Papers Chemistry

Question

Rutherford's scattering experiment is related to the size of the (a) nucleus (b) atom (c) electron (d) neutron

Step-by-Step Solution

Answer

(a) nucleus

Step 1: Understanding Rutherford's Experiment

Rutherford's experiment involved the scattering of alpha particles off a thin sheet of gold foil. The goal was to observe how these particles were deflected as they passed through the foil.

Step 2: Analyzing Observations

Rutherford observed that most alpha particles passed through the gold foil with little or no deflection, but a few were deflected at large angles, and some even bounced back. This unexpected result suggested that a large portion of the atom's mass and positive charge is concentrated in a very small volume.

Step 3: Interpreting the Results

The experiment led to the conclusion that the atom is mostly empty space with a tiny, dense central core where the positive charge and most of the atomic mass reside. This central core was identified as the nucleus.

Step 4: Identifying the Correct Answer

Given the role and conclusions of Rutherford's experiment, the experiment is directly related to identifying and confirming the presence of the nucleus as a dense core within the atom.

Key Concepts

Nucleus

The center of each atom is called the nucleus. This crucial part of the atom contains both protons and neutrons, which are collectively known as nucleons. Protons are positively charged, while neutrons carry no charge at all. This clump of particles makes up almost all of the atom's mass.
It's worth noting that the nucleus occupies only a minuscule space within the atom. Despite its small size, the nucleus holds incredible significance due to its mass and because it influences the atom's overall charge. Rutherford's experiment was groundbreaking as it uncovered this concentrated central core, reshaping our understanding of atomic structure.

Alpha Particles

Alpha particles are a type of particle that consists of two protons and two neutrons tightly bound together. Essentially, they are the same as a helium nucleus. Being positively charged, alpha particles play a key role in the study of atomic structures, as seen in Rutherford's gold foil experiment.
These particles are relatively heavy and travel at significant speeds. When alpha particles encounter an atom, their interactions can reveal key insights into the atom's internal structure. Since the particles are deflected by positive charges, their behavior in scattering experiments helps us understand the arrangement of atoms and their components.

Atomic Structure

The atomic structure refers to the organization of components within an atom. At the center lies the nucleus, containing protons and neutrons. Electrons, which are negatively charged, orbit the nucleus in various energy levels or shells. This simple core structure defines how atoms interact with one another and explains chemical behavior.
Rutherford's findings transformed our view of atomic structure. Previously, scientists thought atoms were like "plum puddings" with charges distributed evenly. The discovery of a small dense nucleus made it clear that most of an atom's volume is actually empty space. This new model gave us a much more accurate understanding of how matter is built.

Gold Foil Experiment

Conducted by Ernest Rutherford in 1909, the gold foil experiment was pivotal in changing the concept of atomic structure. Rutherford and his team fired alpha particles at a thin sheet of gold foil to observe how they scattered. Most particles passed through undisturbed, but some were deflected at large angles.
This experiment showed that atoms have a small, dense center, the nucleus, because only a dense core could explain such deflections. It disproved theories that suggested atoms were spread out uniformly throughout. As a result, the experiment revealed that the atom is mostly empty space, forever changing our perception of atomic models.