Chapter 2 - Atoms and the Atomic Theory - 2-3 Concept Assessment - Page 43: 2-3

1. Cathode rays (electrons) challenges the idea that atoms are indivisible. 2. Isotopes rebuts the idea that all atoms of an element have the same mass. 3. The idea that atoms combine in simple numerical ratios remains valid.

1. Cathode rays (electrons) challenges the idea that atoms are indivisible. 2. Isotopes rebuts the idea that all atoms of an element have the same mass. 3. The idea that atoms combine in simple numerical ratios remains valid.