Percentage abundances and atomic masses (amu) of the natural...

Percentage abundances and atomic masses (amu) of the natural isotopes of an element are given.
(a) Calculate the atomic mass of each element from these data.
(b) Using other information that is available to you, identify the element.
(TABLE CANNOT COPY)

Key Concepts

Isotopes

Isotopes are variants of a chemical element that have the same number of protons but different numbers of neutrons, resulting in different atomic masses. Their existence is fundamental to understanding atomic structure, as the variation in neutron numbers leads to different physical properties, which are important in both chemical and nuclear contexts.

Percentage Abundances

Percentage abundance refers to the relative proportion of each isotope naturally found in a sample of an element. It is typically expressed as a percentage of the total number of atoms present. Understanding these abundances is crucial when calculating the overall average atomic mass of the element.

Weighted Average Atomic Mass

The weighted average atomic mass of an element is calculated by multiplying the atomic mass of each isotope by its relative abundance (expressed as a fraction), and then summing these values. This calculation yields a value that closely reflects the atomic mass as found on the periodic table, taking into account the contribution of each isotope.

Atomic Mass Unit (amu)

The atomic mass unit (amu) is a standard unit of mass that quantifies mass on an atomic or molecular scale, defined as one twelfth the mass of a carbon-12 atom. It allows chemists and physicists to compare masses of atoms and isotopes using a common reference, facilitating the calculation of weighted atomic masses.

Element Identification via Atomic Mass

Identifying an element through its atomic mass involves comparing the calculated weighted average atomic mass with known atomic masses listed on the periodic table. This process helps to determine the specific element by matching the measured or calculated value with the established atomic mass for that element.

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