Calculating Average Atomic Mass
The average atomic mass of an element is the sum of the masses of its isotopes, each multiplied by its natural abundance (the decimal associated with percent of atoms of that element that are of a given isotope). Average atomic mass = f1M1 + f2M2 +…
Furthermore, how do we find average?
Find the average or mean by adding up all the numbers and dividing by how many numbers are in the set.
- The isotopes of chlorine, found in nature are in the ratio 3 : 1.
- The proportion in which the isotopes are found in the nature is always constant.
- Therefore, in any sample of chlorine, the average atomic mass will be,
- = (35 x 75/100) + (37 x 25/100)
- = 105/4 + 37/4.
- = 142/4.
- = 35.5 u.
Correspondingly, what is atomic number formula?
Atomic number = Number of protons
For example, in a sodium atom, there are 11 electrons and 11 protons. Thus the atomic number of Na atom = number of electrons = number of protons = 11.
What is the average atomic mass of chlorine 35 and 37?
Why is average atomic mass calculated?
Why? We need to take into account the percent natural abundances of each isotope in order to calculate what is called the weighted average. The atomic mass of an element is the weighted average of the atomic masses of the naturally occurring isotopes of that element.