Worked example: using the mass number equation | High school chemistry | Khan Academy
Khan Academy・2 minutes read
The mass number equation calculates the number of neutrons in an atom by adding its protons and neutrons. For sodium with a mass number of 23 and atomic number of 11, there are 12 neutrons, while platinum with a mass number of 195 and an atomic number of 78 has 117 neutrons.
Insights
- Mass number equation: Mass number = protons + neutrons. Can determine neutrons in an isotope by subtracting atomic number from mass number.
- Sodium isotope with mass number 23 and atomic number 11 has 12 neutrons; platinum isotope with mass number 195 and atomic number 78 has 117 neutrons.
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Recent questions
What is the mass number equation?
The mass number equation states that the mass number of an atom is the sum of its protons and neutrons.
How do you find the number of neutrons in an isotope?
To find the number of neutrons in an isotope, subtract the atomic number from the mass number.
What is the number of neutrons in a sodium isotope with a mass number of 23 and atomic number of 11?
For a sodium isotope with a mass number of 23 and atomic number of 11, subtracting the atomic number from the mass number gives 12 neutrons.
How many neutrons are in a platinum isotope with a mass number of 195 and atomic number of 78?
In a platinum isotope with a mass number of 195 and atomic number of 78, subtracting the atomic number from the mass number reveals 117 neutrons.
What is the relationship between protons, neutrons, and mass number in an atom?
The mass number of an atom is determined by adding the number of protons and neutrons it contains, showcasing the relationship between these particles in an atom.
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Summary
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Mass Number Equation: Finding Neutrons in Isotopes
- The mass number equation states that the mass number of an atom is the sum of its protons and neutrons. To find the number of neutrons in an isotope of sodium with a mass number of 23 and atomic number of 11, subtract the atomic number from the mass number to get 12 neutrons. For an isotope of platinum with a mass number of 195 and atomic number of 78, subtract the atomic number from the mass number to find 117 neutrons.
