Atomic Structure

Atomic Structure

1. Atoms, Molecules & bonds

   • atoms are the smallest particle of an element. Is still has chemical properties
   • Molecule= 2 or more atoms joined together by attractive forces (bonbs)
     • e.g. Oxygen molecule= 2 oxygen atoms, co2= carbon atom and 2 oxygen atoms
   • size of atom is it's atomic radius= half it's diameter
   • a bond length= distance between the centres of 2 joined atoms
     • typically around 10 m

2. subatomic particles

   • protons & neutrons join together as the nucleus
     • electrons surround nucleus in shells
       • radius of nucleus is 100000x less than the radius of the atom

3. Isotopes

   • same protons and electrons but different amount of neutrons
     • same atomic number but mass number is different
   • different number of neutrons may affect their chemical & physical properties

4. ions

   • charged particles
   • formed when atoms lose ore gain electrons
     • e.g. Sodium atom loses 1 electron to become a sodium ion, oxygen atom gains 2 electrons to become and oxide ion

5. atomic models

   • dalton
     • 1803-john dalton=matter made from atoms
       • all atoms of elements are identical, different elements contain different atoms
     • tiny ball
   • Thomson
     • first subatomic particle=electron 1897
     • atoms contained atoms and are neutral overall
       • plum pudding model= spheres of positive charge with electrons dotted around inside
   • Bohr
     • showed electrons occupy fixed energy or shells around nucleus
   • Rutherford
     • atoms have a positively charged nucleus, but outside the nucleus, electrons orbit the nucleus like planets