How do you calculate the number of neutrons in an element

- How do you calculate the number of neutrons in an element using oxygen as an example
- How do you calculate the number of neutrons in an element using the periodic table
- How do you calculate the number of neutrons in an element's atom
- How do you calculate the number of neutrons contained in an element
- How to calculate the number of neutrons in an atom
- How to find the number of neutrons in an element
- How to calculate number of neutrons in an isotope
- How to find number of protons neutrons and electrons