Which one of the following is not explained by the Dalton's atomic theory?

The correct answer is Presence of different kind of sub-atomic particles in an atom.

Key Points

• Dalton's atomic theory was proposed by John Dalton in 1808 and is one of the earliest scientific theories to describe the nature of matter.
• It explains fundamental concepts such as the law of conservation of mass and the law of constant composition.
• The theory assumes atoms are indivisible and indestructible, which does not account for the existence of sub-atomic particles (protons, neutrons, electrons).
• The discovery of sub-atomic particles in the late 19th and early 20th centuries, such as the electron by J.J. Thomson, revealed limitations in Dalton's atomic model.
• While Dalton's theory was a significant milestone, it does not explain the presence of sub-atomic particles or the internal structure of atoms.

Additional Information

• Law of Conservation of Mass: This law states that mass cannot be created or destroyed in a chemical reaction. Dalton's atomic theory supports this by stating that atoms are indivisible during chemical processes.
• Law of Constant Composition: This law states that a given compound always contains the same proportion of elements by mass, which aligns with Dalton’s idea of fixed atom ratios in compounds.
• Law of Multiple Proportions: This law, formulated by Dalton, states that when two elements combine to form multiple compounds, the mass ratios of the second element to a fixed mass of the first element are in simple whole numbers.
• Sub-atomic Particles: Protons (positive charge), neutrons (neutral charge), and electrons (negative charge) are the fundamental particles that make up an atom. Their discovery refined the atomic model.
• Limitations of Dalton's Theory: It does not explain isotopes (atoms of the same element with different masses) or atomic structure, and it assumes atoms are the smallest indivisible units of matter.