Question

What is the mass number of an ion with 108 electrons, 157 neutrons, and a +1 charge?

Answer 1

Answer : The mass number for this element is 266.

Explanation :

Isotope : It is defined as the element that have the same number of protons but have the different number of neutrons of each of the atom.

Atomic number is defined as the number of protons or number of electrons.

Atomic number = number of protons = number of electrons

Mass number is defined as the sum of number of protons and number of neutrons.

Number of neutrons = Mass number - Number of protons

As we are given :

Number of electrons in an ion = 108

Number of neutrons in an ion = 157

So, number of protons in an ion = 108

For neutral atom, the number of electrons will be:

Number of electrons = Number of protons in an ion + Charge

Number of electrons = 108 + (+1) = 108 + 1 = 109

Now we have to determine the mass number for this element.

Number of neutrons = Mass number - Number of protons

Mass number = Number of neutrons + Number protons

Mass number = 157 + 109

Mass number = 266

Therefore, the mass number for this element is 266.

Answer 2

I'm assuming you mean the atomic mass number for an element on the periodic table. So if there are 108electrons and a +1 charge then there are 109 protons in the atom and therefore the atomic mass unit is 109

Hope this helps!