To calculate the atomic mass of an atom, you need to know the atomic number and the mass number of the atom. The atomic number represents the number of protons in the atom's nucleus, while the mass number represents the total number of protons and neutrons in the nucleus.
Here's how you can calculate the atomic mass:
Subtract the atomic number from the mass number to determine the number of neutrons in the nucleus. Neutrons = Mass number - Atomic number.
Look up the atomic mass of each isotope of the element. Isotopes are atoms of the same element with different numbers of neutrons. The atomic mass of an isotope is typically given in atomic mass units (u) and is found in the periodic table or other reliable sources.
Multiply the atomic mass of each isotope by its natural abundance (given as a decimal or percentage) and sum the products.
For example, let's consider carbon, which has an atomic number of 6 and a mass number of 12. The number of neutrons would be 12 - 6 = 6.
The two most common isotopes of carbon are carbon-12 (with an atomic mass of 12.000 u) and carbon-13 (with an atomic mass of 13.003 u). Carbon-12 is much more abundant, accounting for about 98.9% of natural carbon, while carbon-13 makes up the remaining 1.1%.
To calculate the atomic mass of carbon, you multiply the atomic mass of each isotope by its natural abundance as a decimal and sum the products:
Atomic mass of carbon = (Atomic mass of carbon-12 × Abundance of carbon-12) + (Atomic mass of carbon-13 × Abundance of carbon-13)
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