Question

An atom has a mass number of 25 and 13 neutrons. What is the atomic number of this atom?

Answer 1

The atomic number is `12`, which is the atomic number for magnesium.

Explanation:

The mass number of an isotope is the sum of the protons and neutrons in its atomic nuclei.

If we know the mass number `("A")` and the number of neutrons `("N")`, we can calculate the atomic number `("Z")` by subtracting the number of neutrons from the mass number.

`"A"-"N"="Z"`

`25-13=12`

The atomic number of the element is `12`. Atomic number is the number of protons in the nuclei of all atoms of an element. The element with the atomic number 12 is magnesium.

This is `""^25"Mg"`, or magnesium-25, which can be abbreviated as Mg-25.