The Periodic Table

1. Medeleev/Newlands
2. Both arranged elements by their ATOMIC WEIGHT
3. the list was arranged in a able so elements with similar properties were in the same groups

   Nota:

   • newlands discovered the law of octaves but If the atomic weight was strictly followed it only worked until calcium
4. Mendeleev realised that some had not yet been discovered and left gaps for them

1. electrons/protons/neutrons all discovered in the early 20th centuary
2. now we arrange by atomic (proton) number
3. now all elements are in the appropriate places
4. a table arranged in terms of electronic structures

Nota:

• further down = more reactive, also means it has a lower melting point and boiling point

1. low density
2. react with non-meatals to form ionic compounds
   1. form 1+ ions
   2. form chlorides
      1. white solids, dissolve in water to form colourless solutions
3. react vigorously with water, releasing hydrogen
4. when reacted with water form hydroxides, they are soluble in water and give an alkali solution

1. ductile
2. good conductors
3. hard+strong
4. malleable
5. high densities
6. high mp/bp apart from mercury
7. less reactive and don't react as vigorously w/ water or oxygen
8. form coloured compounds as they have different ions e.g. Fe1 and Fe3
9. good catalysts

1. react w/ metals to form ionic compounds
2. Halide ion carries charge of -1
3. further down the group the element is...
   1. less reactive
   2. higher mp/bp
4. more reactive halogen can displace a less reactive halogen from an aqueous solution of it's salt

Nota:

• more shells = electrons easly lost and less are easily gained