C3.1 The Periodic Table

C3.1 The Periodic Table

1. The Early Periodic Table

   • 19th Century - elements found every year, so they tried to find patterns
     • John Dalton arranged in order of masses
     • 1864 -John Newlands built on Dalton's ideas with the rule of octaves
       • Properties of every 8th Element were similar
       • Assumed all elements had been found
     • Mendeleev
       • 1869 - Dmitri Mendeleev placed in order of atomic weight and arranged to create a pattern
       • Left Gaps

2. The Modern Periodic Table

   • Some of Mendeleev's table had faults
     • Some didn't fit the pattern
     • Some had odd properties
   • 20th century - learned more about structure of the atom
     • Began arranging by proton number
   • Groups
     • react in similar ways
     • Outer shell has same number of electrons
       • Group number tells us what this number is
     • As we go down the group, the atom gets bigger
       • Lose and Gain electrons easily
         • Further away from the neucleus

3. Group 1 - Alkali Metals

   • Contains:
     • Li
     • Na
     • K
     • Rb
     • Cs
     • Fr
       • Radioactive
   • Properties
     • Extremely reactive
     • Stored in oil or reaction with air occurs
     • Low density
     • Soft
     • Shiny before reaction with air but oxide soon is made
     • Lose 1 electron to become a noble gas
     • React with non metals
     • Form an ion of 1+ charge
     • Form ionic compounds
     • Low boiling point
   • Reaction with Water
     • Fizzing because of hydrogen
     • K creates lilac flame
     • Metal hydroxide
     • soluble
     • solution with a high pH
   • Other Reactions
     • With chlorine makes metal chloride
     • Ionic compounds of alkali metals are usually white

4. Transition Elements/Metals

   • Physical Properties
     • Conduct electricity and energy
     • Hard and strong
     • Very dense
     • High melting point
   • Chemical Properties
     • Not as reactive as group 1.
     • Corrode Slowly
     • Good structural properties
   • Compounds of the metals
     • Coloured compounds
     • Transition elements can form more than one ion (hence the roman numeral)
     • Useful as catalysts

5. Group 7 - The Halogens

   • Properties
     • Poisonous non metals
     • coloured vapour
     • Low Melting and Boiling points
     • Poor conductors
   • Reactions
     • 7 outer shell electrons
     • Both ionic and covalent bonding
     • With metals
     • Non metals gives covalent bond
     • Displacement Reactions
       • Use a more reactive halogen to displace another from a salt solution