Question

An isotope with a `1^+` charge has `107` electrons and `159` neutrons. What is its mass number? What is the element?

Answer 1

The mass number of an isotope is the sum of the protons and neutrons in the nucleus of the atom.

In a neutral atom, the number of protons and electrons are equal. However, the ion has 107 electrons and a `"1"^+` charge. This means that the original atom lost one electron, and there were originally 108 electrons in the neutral atom.

Because the number of protons in the atoms of an isotope is the same for all atoms of an element, the number of protons in this isotope is 108. The number of neutrons is given as 159. The mass number is 108 + 159 = 267.

The number of protons is the atomic number of an element, so we can identify the element on the periodic table, which is Hassium, Hs. We can use nuclear (isotopic) notation to represent the ion of this isotope, which is as follows: `""_108^267 "Hs"^(+)`