If atoms
are made of smaller parts such as electrons,
why are atoms considered the basic unit of
matter? Summarize the evidence supporting
the claim and explain the reasoning.

Which of the following is an example of physical change not a chemical change? a) a log gives off heat and light as it burns. b) a tree stores energy from the sun in its fruit. c) a penny lost in the grass slowly changes color. d) a water pipe freezes and cracks on a cold night.