Which part of the atom has to stay the same for it to be the same element? number of neutrons
number of protons
number of electrons
number of protons, neutrons, and electrons

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.