Defining Isotopes
- Isotopes are atoms of the same element that contain the same number of protons and electrons but a different number of neutrons
- The name of an isotope is the chemical symbol (or word) followed by a dash and then the mass number
- Eg. carbon-12 and carbon-14 are isotopes of carbon containing 6 and 8 neutrons respectively
- The chemical symbol of an isotope will still be shown in the usual form, as shown:
A general chemical symbol
Isotopes of the same element have the same chemical symbol with a different mass number
- For chemical symbols, isotopes have:
- The same chemical symbol
- e.g. isotopes of chlorine all have the symbol Cl
- The same atomic number
- e.g. isotopes of chlorine all have an atomic number of 17
- A different mass / nucleon number
- e.g. the chlorine-35 isotope has a mass number of 35, while the chlorine-37 isotope has a mass number of 37
- The same chemical symbol
The atomic structure and symbols of three isotopes of hydrogen
All three hydrogen isotopes have the chemical symbol H, the same number of protons but a different number of neutrons