Isotopes

Isotopes

1. Not all atoms of an element have the same number neutrons.

2. Atoms of the same element with different masses are called isotopes

3. the proportion of each isotope is fixed

   • it is the same in both the pure element and in the compounds containing that element

4. because isotopes have the same number of electrons, they all react in exactly the same way

5. some elements have radioactive isotopes which decay over time

6. knowing how quickly the isotopes decay, scientists can work out the age of archaelogical remains such as Egyptian mummies

   • carbon dating-14 is used for remains suspected of being up to 60 000 years old
   • Older samples need different isotopes. Uranium were used to calculate the age of the earth
   • Fossils are dated by dating the rocks in which they found