In nickel-78, there are 28 protons, 28 electrons, and 50 neutrons.
The protons is always the atomic number.
The electron would always be the atomic number when it's a neutral atom. (Different for isotopes)
The neutrons is always the number that makes up the mass with protons. You can figure it out by subtracting atomic mass by protons. (78-28 = 50)
Physical changes occur when objects or substances undergo a change that does not change their chemical composition. This contrasts with the concept of chemical change in which the composition of a substance changes or one or more substances combine or break up to form new substances.
It can allow the molecule (like water) to be polar because it has a negative and positive side to it (oxygen holds the negatives tight causing the hydrogens to be positive).
