Module 3 periodic table

Periodicity-  regular periodic variation of properties of elements with atomic number and position in the Periodic Table- trend in properties that are repeated across each period

Trends across period- number of protons increases, atmoic radius decreases, attraction between nucleus and outer electrons increases,first ionisation energy increases, electron shielding hardly changes

Trends down a group- number of shells increases, shielding increases, atmoic radius increases, weaker attraction on the outer electrons, first ionisation energy decreases

• Group 1 to 4 = increase in boiling point
• Group 4 to 5 = sharp decrease in boiling point 
• Group 5 to 0 = comparatively low boiling point

• Giant metallic -> giant covalent -> simple moleculare structures
• Giant metallic- strong forces between negative delocalised electron and positive ions - metallic bonding
• Giant covalent- strong forces between atoms - covalent bonding
• Simple molecular structure- weak forces between molecules - van der waals forces

• Na to Al- ionic charge increases, ionic size decreases, number of outer electrons increases, attraction increases, melting and poiling points increase

• reactive, strong reducing agents, oxidise in reaction, lose two electrons
• reactivity increases down the group
• decrease in ionisation energy
• reacts with oxygen vigorously- redox reaction
• reacts with water to form a hydroxide and hydrogen 
• solubility increases
• alkalinity increases
• ease of thermal decomposition decreases
• calcium hydroxide- lime to neutralise acid soils
• magensium hydroxide - milk of magneria to relieve indigestion 

• low melting and boiling points
• diatomic
• boiling point increases down group- increase in electrons- increase in van der waals' 
• move from gas to solid down the group
• oxidising agents - remove electrons - gains an electron 
• oxidising power decreases down the group as reactivity decreases 
• Cl2- green in water and cyclohexane 
• Br2 - orange in water and cyclohexane 
• I2 - brown in water and violet in cyclohexane 
• Disproportionation reactions:
  -   Cl2 + H2O -> HClO + HCl  (kill bacteria) 
  -   Cl2 + 2NaOH -> NaCl + NaClO + H2O  (bleaching) 
• simple molecular - weak van der waals' forces 
• 1/2 X2 + e- -> X-   halogen + electron -> halide ion 
• chloride - white precipitate, soluble in dilute NH3 
• bromide - cream preciptate, soluble in conc NH3 
• iodide - yellow preciptate, insoluble in conc NH3