Elements, Compounds and Isotopes

Elements, Compounds and Isotopes

1. Elements

   • Consist of one type of Atom only
   • A lot of everyday substances are Elements
   • E.g.
     • Copper
     • Alluminum
     • Oxygen

2. Compounds

   • Compounds are chemically bonded
   • Compounds are formed when 2 or more elements are chemically react together
   • It's difficult to seperate the 2 elements once they've been put together
   • The properties of a compound are completely different to the ones of the original element
   • E.g. Carbon dioxide is a compound formed by elements Oxygen and Carbon

3. Isotopes

   • Isotopes are the same except for an extra neutron or two.
   • Different atomic form of the same element
   • Same number of protons, different number of neutrons
   • Isotopes must have the same proton number but a different mass.
   • If they had a different proton number it would be a different element all together
   • E.G. Carbon-12 & Carbon-14
     • Carbon-12
       • 6 Protons
       • 6 Neuterons
       • 6 Electrons
     • Carbon-14
       • 6 Protons
       • 8 Neutrons
       • 6 Electrons
     • Carbon-14 is unstable.

4. Electron shells

   • Electrons always occupy shells
   • Lowest energy levels are always filled first ( ones closest to the nucleus)
   • Only a certain amount of electrons are allowed in 1 shell
   • 1st shell - 2 2nd shell - 8 3rd shell - 8
   • Atoms are 'happier' if they have full electron shells, Like the Noble gasses and group 0 elements
   • Most atoms haven't got a full outer shell, this makes the atom want to react