What is the mass number of boron?
Answer 1:
Well it depends on the isotope….
Explanation:
\(Z=5,\) and thus WE KNOW that we got the element boron.
To a first approx. \({ }^{11} B\) is 80% abundant, and clearly (why?) this isotope has 6 nucular neutrons and thus a mass number of \(11\)…..and \({ }^{10} B\) is 20% abundant, and clearly (why?) this isotope has 5 nucular neutrons and thus a mass number of \(10;\) and a neutron is simply a massive nuclear particle with ZERO electronic charge.
Answer 2:
The mass number of the most common isotope of boron is 11.
Please see the more detailed explanation below.
Explanation:
This is a slightly tricky question, because a mass number is for a particular isotope of an element, not the element itself.
Element number 5 is boron (B). That means every atom of boron has 5 protons.
The most common isotope (about 80% of naturally occurring boron) of boron has 6 neutrons too, for a total of 11 nucleons (protons + neutrons). Its mass number is 11.
Some naturally occurring boron (about 20%) has 5 neutrons, for a total of 10 nucleons, and a mass number of 10.
It is also possible to make isotopes with more than 6 or less than 5 neutrons.
The mass number of the most common isotope of boron is 11.