If an atom has an atomic number of 9 and an atomic mass number of 19, how many protons, neutrons, and electrons does it have?
These isotopes of fluorine have 9 proton, 9 electrons and 10 neutrons. Explanation: The atomic number is the number of protons (p+). In a neutral atom, the number of electrons (e−) equals the number of protons. The mass number is the sum of the protons and neutrons of a particular isotope. Subtract the atomic number from the mass number to get the number of neutrons. Mass number − atomic number = number of neutrons. There are: 9 protons 9 electrons 10 neutrons Fluorine is the element in question, as its atomic number is 9. The nuclear or isotopic notation would be 19 9 F .
