Chemistry: Atoms and Molecules

Why did the discovery of electrons and protons inside the atom lead to the failure of Dalton's atomic theory?

Which scientist was the first to propose a model for the structure of an atom?

What did J.J. Thomson propose about the structure of an atom?

According to J.J. Thomson, how are the negative and positive charges distributed within an atom?

What did J.J. Thomson receive the Nobel Prize in Physics for in 1906?

How did J.J. Thomson describe the atomic structure based on his model?

What was the major contribution of J.J. Thomson to the understanding of atomic structure?

In J.J. Thomson's model, how did he explain the overall charge neutrality of an atom?

How did J.J. Thomson's atomic model differ from Dalton's atomic theory?

Atoms and Molecules

Atoms and molecules are the fundamental building blocks of matter.
Different kinds of matter exist due to different atoms constituting them.

Structure of the Atom

Atoms are not indivisible, and scientists have proposed various models to explain their internal structure.
The elucidation of the structure of atoms is based on a series of experiments.

Charged Particles in Matter

Studying static electricity and the conditions under which electricity is conducted by different substances provides evidence that atoms are not indivisible.
A dry comb can attract small pieces of paper, demonstrating the presence of charged particles in matter.

Atomic Mass

The average atomic mass of chlorine is 35.5 u, indicating that a sample of chlorine contains both isotopes of chlorine.
The average atomic mass does not mean that any one atom of chlorine has a fractional mass of 35.5 u.

Sub-atomic Particles

Electrons, protons, and neutrons are the three sub-atomic particles of an atom.
J.J. Thomson discovered electrons and proposed that they are embedded in a positive sphere.
E. Goldstein discovered protons, and J. Chadwick discovered neutrons.

Models of the Atom

Rutherford's alpha-particle scattering experiment led to the discovery of the atomic nucleus.
Rutherford's model of the atom proposes that a very tiny nucleus is present inside the atom, and electrons revolve around this nucleus.
Neils Bohr's model of the atom proposes that electrons are distributed in different shells with discrete energy around the nucleus.
According to Bohr's model, if the atomic shells are complete, the atom will be stable and less reactive.

Explore the structure of atoms and molecules in Chapter 3. Discover how atoms and molecules are the fundamental building blocks of matter, leading to the diverse properties of different elements. Delve into questions about the differences between atoms of various elements and the indivisibility of atoms.