Question

Which of the following is not a correct statement according to Rutherford's atomic model? (a) \(99 \%\) of mass of an atom is centred in the nucleus. (b) Most of the part inside the atom is empty. (c) The size of nucleus is very small in comparison to the atoms. (d) Electrons revolve round the nucleus.

Short answer

(d) Electrons revolve round the nucleus is not a correct statement according to Rutherford's model, as it does not account for the modern understanding of electron behavior.

Step-by-step solution

Understanding Rutherford's Atomic Model

Rutherford's atomic model, proposed by Ernest Rutherford, describes the atom as having a tiny, dense, positively charged nucleus where all the mass of the atom is concentrated. Electrons orbit this nucleus, and the rest of the atom is mostly empty space.

Analyzing Each Statement

Examine each option to determine if it aligns with the traits of Rutherford's model: (a) refers to mass concentration in the nucleus, (b) suggests that atoms are mostly empty space, (c) compares the size of the nucleus to the atom, and (d) describes electron behavior.

Identifying the Incorrect Statement

Rutherford's model does suggest that electrons orbit the nucleus, but it does not account for the nature of their motion. According to modern quantum mechanics, electrons do not revolve in fixed paths but rather exist in regions called orbitals. Therefore, the notion of electrons 'revolving' around the nucleus in set paths is outdated and incorrect.

Key concepts

Atomic Structure

At the heart of understanding the material world is the concept of atomic structure. This idea is pivotal to explaining why materials behave the way they do. Rutherford's atomic model pioneered this understanding by proposing that an atom consists of a central nucleus surrounded by electrons.

According to Rutherford, the nucleus is densely packed with protons and neutrons, which account for nearly all of an atom's mass. However, the electrons, which possess much less mass, occupy the vast empty space around the nucleus. This model was a significant shift from previous thoughts, where it was believed that an atom was a solid sphere without any distinguishable internal structure. Yet, Rutherford's concept was just the beginning. It couldn't explain some atomic behaviors, such as how electrons stayed in motion around the nucleus without collapsing into it – a question that would be answered by the development of quantum mechanics.

Nuclear Physics

Diving deeper into the atom brings us to nuclear physics, the study of atomic nuclei and their constituents. Rutherford's model placed the nucleus at the center of the atom's universe, so to speak. This tiny core contains protons and neutrons, and this is where the strong nuclear force comes into play.

The strong nuclear force is one of the fundamental forces in physics, and it governs the stability and structure of the nucleus by keeping protons and neutrons together despite the repulsive electrostatic forces between positively charged protons. The discovery of the nucleus and the subsequent development of nuclear physics propelled many advances, including nuclear power generation and medical imaging techniques. However, nuclear physics also leaves many questions unanswered, which is where quantum mechanics steps in to complete the picture.

Quantum Mechanics

Quantum mechanics revolutionized our understanding of atomic and subatomic particles by introducing a probabilistic approach to the behavior of electrons. Unlike Rutherford's orbits, where electrons were thought to circle the nucleus like planets around the sun, quantum mechanics describes electrons in terms of probabilities and 'orbitals', which are more like clouds where electrons are likely to be found rather than precise orbits.

This model is fundamental in explaining the chemical bonding and properties of elements. Variables such as energy levels, angular momentum, and magnetic spin come into play to describe an electron's behavior. Quantum mechanics also helps to understand how electrons transition between energy levels, emitting or absorbing energy in the form of photons, which explains phenomena like atomic spectra. Thus, the notion that electrons revolve in fixed paths is a relic of pre-quantum thinking and has been replaced by a more accurate and nuanced quantum model.