In a physical change the appearance or form of the matter changes but the kind of matter in the substance does not. However in a chemical change, the kind of matter changes and at least one new substance with new properties is formed. Hope this helps!
An atomic number is <span>the number of protons in the nucleus of an atom, which determines the chemical properties of an element and its place in the periodic table or chart.</span>
1Hz = 1 cycle per second
19 cycles / .5 seconds = 38Hz
