A neutral isotope has 45 neutrons and 36 electrons. Identify the element symbol of this isotope and determine the mass number and number of protons. element symbol: mass number: number of protons:

Kr, mass number 81, number protons 36.

Explanation:

If the atom has 36 electrons, and it is neutral, it has 36 protons. 36 protons means that this element has atomic number = 36. This is Kr.

Mass number = number protons + number neutrons = 36 + 45 = 81