chem modelsofparticulatenatureofmatter
Structure 1.2.2 - isotopes are atoms of the same element with different numbers of neutrons
isotope:
- atoms of the same element with different numbers of neutrons
- have same chemical properties
- differ in physical properties
- mp and bp - heavier particles move more slowly at a given temperature 1.1.3 kinetic energy and temperature
isotopes are responsible for decimal relative atomic masses:
- the average mass of an element
e.g. chlorine, which exists as two isotopes,
to work out the percentage abundance of the isotopes from the relative atomic mass:
the stability of a nucleus depends on the balance between the number of protons and neutrons. an unstable nucleus that contains too many or too few neutrons becomes more stable by going through radioactive decay.
these are known as radioisotopes
challenge questions
- Suggest why isotope nuclear enrichment plants based on gaseous diffusion are so large.
The difference in mass between U-235 and U-238 is very small, so molecules can only be separated by large distances.
- Use the periodic table in the data booklet to identify an element with an atomic number of less than 80 which has no stable isotopes.
Technetium -