A) a column
example: earth alkaline metals
Answer:
This means that the isotope of silicon with a mass number of 28 is by far the most common of these three isotopes.
Explanation:
The abundance of Si-28 is 92.23%. Si-29 is 4.68% and Si-30 is 3.09%.
Because most Si atoms have a mass of 28 amu, the average mass of all silicon atoms is very close to 28.
Here is a video which summarizes how to calculate average atomic mass from data about mass and relative abundance.
Mass number<span> is the </span>number<span> of protons </span>and<span> neutrons in an atom.
</span>Atomic mass<span> is the average </span>mass<span> of all the isotopes of a certain type.</span>
<span>The transferred electron from lithium to fluorine provides each atom with a full outer energy level.</span>
