Understanding Isotopes
* Isotopes are atoms of the same element that have the same number of protons but different numbers of neutrons. This means they have the same atomic number but different atomic masses.
* Atomic Mass: The average mass of all the isotopes of an element, taking into account their relative abundances.
Calculating Atomic Mass
1. Identify the Isotopes: Determine the isotopes present in the mixture and their respective masses.
2. Determine the Abundance: Find the percentage abundance (or fractional abundance) of each isotope. This is often given in the problem or can be found in a periodic table.
3. Weighted Average: Multiply the mass of each isotope by its abundance (as a decimal) and then sum up the results.
Formula:
Atomic Mass = (Mass of Isotope 1 × Abundance of Isotope 1) + (Mass of Isotope 2 × Abundance of Isotope 2) + ...
Example
Let's say you have an element with two isotopes:
* Isotope 1: Mass = 10.01 amu, Abundance = 90%
* Isotope 2: Mass = 11.01 amu, Abundance = 10%
Calculation:
Atomic Mass = (10.01 amu × 0.90) + (11.01 amu × 0.10)
Atomic Mass = 9.009 amu + 1.101 amu
Atomic Mass = 10.11 amu
Important Note: Atomic masses are usually expressed in atomic mass units (amu).
