3.3.1 Discuss the similarities and differences in the chemical properties of elements in the same group.

Group 1

• Group 1 metals = Alkali Metals
• share similarities and differences in their chemical properties.
• reactive, especially with air and water 
• often stored in paraffin to avoid contact with air
• react quite vigorously with water
• ex) lithium with water will most likely lead to a slow reaction
• ex) caesium with water is almost an explosion
• reactivity increases down the group because of decreasing electrostatic attraction to outer shells, therefore electrons can be lost easily.
• good reducing agents because they donate electrons
• the reaction is exothermic (releases energy) 
• metal hydroxide and hydrogen
• first two float
• might ignite and produce a flame (ex) potassium = violet flame 

Alkali Metals reactions with water

• A = generic alkali
• 2A (s) + 2H2O (l) → 2AOH (aq) + H2(g)
• Alkali metal + Water →Metal hydroxide + hydrogen
• We can also write this reaction in its ionic form, as alkali metals form ionic compounds:
• 2A (s) + 2H2O (l) →2A+ (aq) + 2OH- (aq) + H2 (g)

Group 7: Halogens

• 7 outer electrons
• reactivity decreases down the group because the distance between the nucleus and outer-electron increases as you go down the group
• are good oxidizing agents because they accept electrons easily

Halogens reaction with alkalis

• A = generic alkali
• Ha = generic halogen
• Halogen reaction with alkali's
• 2A (s) + HA2→2AH2 (s) = 2KBr +Cl2 → 2KCl +Br2 
• chlorine = gaseous state
• bromine = liquid state
• iodine = solid state 
• after reaction known as a halide
• produce a salt
• we often call this “Displacement reactions”

Group 0/8 : Nobel Gases

• colorless gases
• monoatomic 
• very unreactive because they do not gain or lose electrons
• stable octect (full outer shell)