Question

what new characteristic did john dalton add to the model of the atom?
an atom is a round, solid mass.
an atom has a massive, positive center.
an atom is made up of smaller particles.
an atom can join with other kinds of atoms.

Explanation:

• The idea of a round, solid atom was proposed by early Greek philosophers (like Democritus), not Dalton.
• The massive positive center (nucleus) was part of Rutherford's atomic model, not Dalton's.
• The concept of atoms being made of smaller subatomic particles came after Dalton's work (from Thomson, Rutherford, etc.).
• Dalton's atomic theory included the postulate that atoms of different elements can combine with one another in fixed, simple whole-number ratios to form compounds, meaning atoms can join with other kinds of atoms.

Answer:

D. An atom can join with other kinds of atoms.