Question

which of the following ideas about the atom changed when new evidence was discovered?
a. elements are different kinds of atoms.
b. all matter is made up of atoms.
c. atoms are made up of smaller particles.
d. atoms cannot be divided.

Explanation:

Initially, the idea was that atoms cannot be divided. But with the discovery of sub - atomic particles like electrons (by J.J. Thomson), protons (by Ernest Rutherford), and neutrons (by James Chadwick), this idea was proven wrong. Atoms are made up of smaller particles.

• Option A: The concept that elements are different kinds of atoms is still valid. Different elements have atoms with different numbers of protons (and other properties).
• Option B: The idea that all matter is made up of atoms is a fundamental and still - valid concept in chemistry.
• Option C: This is a correct and updated idea based on evidence (discovery of sub - atomic particles).
• Option D: This was an early idea (like in Dalton's atomic theory) which was changed when sub - atomic particles were discovered.

Answer:

D. Atoms cannot be divided.