How Do You Find The Relative Atomic Mass Of A Substance?
The International Union of Pure and Applied Chemistry (IUPAC) defines the relative atomic mass as the ratio of an atom’s mass to 1/12 of the mass of an atom of isotope carbon-12. Isotopes of a chemical element have the same number of protons but they have varying numbers of neutrons. For instance, the isotope nitrogen-14 has seven protons and neutrons, while nitrogen-15 consists of seven protons and eight neutrons. To determine the relative atomic mass of an element, it is necessary to take into account its isotope percent composition. As an example, we will determine the relative atomic mass of the metal Chromium (Cr) that has atomic number 24. Step 1 Find the element of interest in Table 1 of the IUPAC report (Reference 1) using data given in the column “Isotope compositions.” In our example, chromium (Cr) has four isotopes: Chromium-50: 4.345 percent Chromium-52: 83.789 percent Chromium-53: 9.501 percent Chromium-54: 2.365 percent Step 2 Multiply each isotope mass by its percent com
