The relative atomic masses of elements, Isotopes

Isotopes Definition: Isotopes are atoms with the same number of protons, but differing numbers of neutrons. Isotopes are different forms of a single element.

Examples: Carbon 12 and Carbon 14 are both isotopes of carbon, one with 6 neutrons and one with 8 neutrons (both with 6 protons).

ATOMIC WEIGHTS AND ISOTOPIC ABUNDANCE

The atomic weight of an element is the relative atomic mass of that element. It is actually a weighted mass of the elements isotopes (if any) and their relative abundance.

You know that the sum of the percentages of the isotopes is equal to 1 (100%), so the relative abundance of the isotopes can be found using simple algebra.

EVALUATION

1.            Define the following terms i. Atomic number   ii. mass number iii. Isotopes iv. Isotopy

2.            Determine the relative atomic mass of carbon from a sample with the following data.98.9% of carbon -12 and 1.1% of carbon-13.