Atoms do not change during a chemical change. They do not either during a physical change.
During a chemical change molecules change but not the atoms. The atoms separate from the original molecules and form new molecules. Then moleculas change but atoms remain being the same before and after the chemical change.
For example, atoms of oxygen in molecules of O2 combine with atoms of hydrogen in molecules of H2 and they form the molecules of water H2O.
The atoms of O in O2 are the same atoms of O in H2O and the atoms of H in H2 are the same atoms of H in H2O. The molecules changed, from H2 and O2 to H2O, but the atoms are the same.
From what i know, the feet of an animal should always be on the table. This is due to the fact that aside from health reason's, the animal usually feels more comfortable not on it's back.
