Nickel has chemical symbol Ni and the atomic 28. How many protons, neutrons, and electronic would be found in an atom of nickel-78

Atomic number is the sum of only total number of protons present in an element. Whereas mass number or atomic mass is the sum of total number of both protons and neutrons present in an element.

For example, given atom of Ni has atomic number 28. And, it is known that atomic mass of Ni is 58 g/mol.

Therefore, number of neutrons present in it will be calculated as follows.

Mass number = no. of protons + no. of neutrons

58 = 28 + no. of neutrons

no. of neutrons = 58 - 28

= 30

Also, when an atom is neutral in nature then its number of protons equal to the number of electrons present in it.

Hence, we can conclude that in a neutral atom of Ni there are 28 protons, 30 neutrons and 28 electrons.

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)