Question

Which parts of Dalton's atomic theory are no longer true today?

A) Atoms are indivisible.
B) Atoms of the same element are identical.
C) Atoms combine in simple whole number ratios.
D) Atoms have no internal structure.

Answer 1

Some parts of Dalton's atomic theory have been revised: atoms can be subdivided into subatomic particles, they can have different masses even within the same element (isotopes), and they possess an internal structure with nucleus and electrons.

Step-by-step explanation:

The parts of Dalton's atomic theory that are no longer considered true today are:

• Atoms are indivisible: Modern science has shown that atoms can be subdivided into smaller particles such as protons, neutrons, and electrons.
• Atoms of the same element are identical: It is now known that atoms of the same element can have different masses, known as isotopes. For example, chlorine atoms can have mass numbers of 35 and 37.
• Atoms have no internal structure: We now understand that atoms have a complex internal structure, which includes a nucleus and electron clouds.

Despite these revisions, aspects of Dalton's theory, such as atoms combining in simple whole number ratios to form compounds, remain fundamental to modern chemistry.