Atomic Structure

Atomic Structure

1. Definitions

   • An atom= The smallest particle of an element that can exist in its own stable enviroment
     • Element= A substance that consists of only one type of atom and cannot be broken down into anything simpler by chemical means
       • Isotopes= atoms of an element with the same atomic numbers but different mass numbers
         • RAM= The average mass of an atom of an element relative to 1/12th the mass of an atom of Carbon -12
           • Abundance= amount of each isotope present
             • Mass Number= Total number of protons and neutrons in the nucleus
               • Ion= A charged particle formed when an atom looses or gains electrons negative=anion positive cation
                 • Atomic Number= The number of protons in the nucleus of an atom

2. Calculating RAM

   • (Mass number of 1st isotope * abundance) + (Mass number of 2nd isotope * abundance) / Total abundance

3. Timeline

   • 1808- John Dalton said all elements where made up of tiny particles called atoms
     • 1897- J.J. Thompson discovered the electron and suggested that all the negative electrons were in sphere of positive charge
       • 1913- Rutherford suggested the atom had a positive nucleus and electrons orbited it
         • 1932- Chadwick discovered nucleus
           • Why did the nucleus take so long to be discovered?
             • Neutrons have 0 charge meaning they were not deflected by magnetic fields

4. Ions

   • A full outer shell means the atom is stable, which is done by either losing or gaining electrons
   • Metal elements usually form positive ions and non metal elements normally form negative ions and the end of the name changes to ide