Answer and Explanation:
To calculate the atomic mass of an element, you need to know the data about the isotopes of that element. Isotopes are atoms of the same element that have different numbers of neutrons, resulting in different mass numbers.
Here are the key data you need to know about the isotopes of an element:
1. Mass Number (A): The mass number represents the total number of protons and neutrons in the nucleus of an atom. Each isotope of an element has a unique mass number. You need to know the mass numbers of all the isotopes of the element.
2. Relative Abundance (X): The relative abundance of an isotope refers to the proportion or percentage of that isotope in a naturally occurring sample of the element. It is important to know the relative abundances of the isotopes to calculate the atomic mass.
3. Atomic Mass (M): The atomic mass of an element is the weighted average of the masses of its isotopes, taking into account their relative abundances. It is calculated using the formula:
Atomic mass = (Mass1 × Abundance1) + (Mass2 × Abundance2) + ... + (Massn × Abundancen)
In this formula, Mass1, Mass2, etc., represent the mass numbers of the isotopes, and Abundance1, Abundance2, etc., represent their relative abundances.
By knowing the mass numbers and relative abundances of the isotopes, you can calculate the atomic mass of the element using the weighted average formula.
For example, let's consider the element carbon. Carbon has two stable isotopes: carbon-12 (with a mass number of 12) and carbon-13 (with a mass number of 13). The relative abundance of carbon-12 is about 98.9%, and the relative abundance of carbon-13 is about 1.1%.
To calculate the atomic mass of carbon, we can use the formula:
Atomic mass = (12 × 0.989) + (13 × 0.011) = 12.01
Therefore, the atomic mass of carbon is approximately 12.01 atomic mass units (amu).
In conclusion, to calculate the atomic mass of an element, you need to know the mass numbers and relative abundances of its isotopes and use the weighted average formula to determine the atomic mass.