What is the mass number and the atomic number of Boron-11?
In your case, the name boron-11 is used to designate an isotope of boron that has a mass number equal to
Since mass number is defined as the sum of the number of protons and the number of neutrons the atom has in its nucleus, it follows that you can write
#color(blue)(A = Z + "no. of neutrons")" "#, where
As you know, the identity of an element is given exclusively by the number of protons it has in its nucleus. This number represents the element's atomic number.
So, to identify the atomic number of boron, take quick look at a periodic table. Notice that boron,
This means that any atom that has
So, the mass number of this boron isotope is equal to