Periodic Table

Periodic Table

1. How the elements are laid out

   • Organised by the element's atomic number
     • Ordering by atomic number ordered some of the problems with Mendeleev's table
       • For example Iodine which has a mass of 127 should be put before Tellurium (mass of 128) because Iodine has a smaller mass
         • iodine has similar properties to Bromine, Chlorine and Flourine. So he broke his own rule and put Iodine in their column.
       • Modern Periodic Table is ordered by atomic number which puts Tellurium before iodine without breaking any rules.
       • New elements aren't being found anymore, but scientists are making new radioactive ones. this means they have very little life span because they decay very quickly.
         • if we could place them on the Periodic Table then we would have a better idea about their properties
   • Atomic mass is Neutrons + Protons in the atom
     • Atomic Number is how many Protons there are (the amount of Protons is the same as the amount of Electrons)
   • easiest way to split the Periodic Tables is into Metals and Non Metals, Metals dominating the left hand side and Non Metals on the right.

2. What are groups in the Periodic Table

   • Group 1: Lithium, Sodium, potassium, Rubidium, Caesium and Francium. They all have 1 Electron in their outer shell. Allso the number of shells tells you which row they are on. 2 shells goes on second row, 3 shells on row 3 and so on.
     • All tarnish quickly in air and quicker as you go down the group
       • All have a violent reaction with water in the same fashion
     • They outer electron is easily lost, and the other electrons don't help the nucleus hold onto the atom, this is called shielding.

3. Group 1 are Alkali Metals becuase they react with water to make an alkaline solution, as seen by dropping one into a trough of water adding universal indicator and it turn blue or purple (pH 8-12)