The difference between an allegory and a symbol is that an allegory is a complete narrative that conveys abstract ideas to get a point across, while a symbol is a representation of an idea or concept that can have a different meaning throughout a literary work.
Two small aluminum spheres, each of mass 0.0250 kilograms, are separated by 80.0 centimeters. How many electrons does each sphere contain? (The atomic mass of aluminum is 26.982 grams per mole, and its atomic number is 13.) The attempt at a solution I said that there are 6.02*10^23 atoms in a mole, and noted that after converting the mass into grams each sphere has .9265 moles. If the Aluminum spheres are uncharged there are 13 electrons per atom.
The number of protons an atom has in its nucleus is given by the atomic number. A quick looks in the periodic table will show that aluminium has an atomic number equal to #13#. This means that any atom that is an isotope of aluminium will have #13# protons in its nucleus. Since you're dealing with a neutral atom, the number of electrons that surround the nucleus must be equal to the number of protons found in the nucleus. Therefore, the aluminium-27 isotope will have #13# electrons surrounding its nucleus. Finally, use the known mass number to determine how many neutrons you have.