How do we now that caramelizing suger is a chemical change

If the atomic mass of an atom is 34 and the atom contains 13 protons, how many neutrons does the atom contain?

What material does not melt at any temperature

Sally is making a model of a magnesium atom with an atomic mass number of 24 for her chemistry class. she has foam balls for the protons, neutrons, and electrons. she has added 6 neutrons to her model so far. how many more neutrons does she need to add to complete her neutral atom of magnesium?