CHEMISTRY - unit 1 - the periodic table

CHEMISTRY - UNIT 1

The periodic table - shows the elements in order of increasing atomic number

Elements in the same group in the periodic table have similar chemical properties. This is because their atoms have the same number of electrons in their outer shells.

GROUP 1 - alkali metals

• Low melting and boiling points
• Low densities
• React quickly with water and oxygen to produce hydroxides and oxides
• Their hydroxides and oxides dissolve in water to form strong alkali solutions.

GROUP 0 - noble gasses

• Very unreactive because they have full outer shells

All atoms want complete outer shells. Atoms in group 1 are very reactive because they want to get rid of their single outer electron (this would be easier than trying to get seven more). They are more reactive than transitional metals because they are closer to a full shell. Halogens are equally very reactive because they only need one electron to get a full outer shell. Noble gasses are very unreactive because they have a full outer shell so don't need to react. They are stable.