Atomic Structurs

Atomic Structurs

1. Proton- Relative mass 1, Relative charge +1 Neutron- Relative mass 1, Relative charge 0 Electron- Relative mass 1/1836, Relative charge -1

2. Mass Number, A =number of protons + number of neutrons

3. Atomic Proton Number, Z = number of protons

4. Every single atom of any particular element has the same number of protons in it nucleus and therefore the same number of electrons. But the number of neutrons may vary.

   • ISOTOPES
     • Atoms with the same number of protons but different numbers of neutrons called isotopes
     • Different isotopes of the same element react chemically in exactly the same way
     • Atoms of different isotopes of the same element vary in mass number because of the different number of neutrons in their nuclei

5. CARBON DATING

   • Sometimes isotopes are unstable, so nucleus breaks down giving off either bits of its nucleus or energetic rays
     • This is the cause of radioactivity
       • Radioactive isotopes decay at a at a rate measured by its half life, this is the time taken for all of its radioactivity to decay
   • Carbon 14 is a radioactive isotope, half life = 5730 years and is found in all living matter.
     • Scientists can date organic matter as once living material dies, C is no longer taken in so radioactive carbon breaks down, so by knowing the half life scientists can work backwards.

6. ENERGY LEVELS

7. Ionisation energy - The energy required to remove a mole of electrons from a mole of isolated gaseous atoms or ions

8. Relative atomic mass - Is the ratio of the average mass of one atom of that element to 1/12th of the mass of one atom of carbon 12