• Group VII (7 outermost shell e-)
• smell: pungent, acidic
• hazard warning labels: toxic, corrosive

• Collection method: Gas syringe/downward delivery
• Drying method: Bubbling through conc. H2SO4

Chlorine

• color: yellowish green
• Preparation methods:

(1) By adding dilute acid to chlorine bleach OCl- + Cl- + 2H+ -> Cl2 + H2O (2) Reacting conc HCl and MnO4-

• Test for Cl2(g): It turns moist pH paper red and then white

Cl2 + H2O -> HCl + HOCl HOCl+ (dye) -> HCl + (dye + O)

• act as bleaching agent

Cl2(g)reacts with cold dilute naoh to give chlorine bleach Cl2 + 2NaOH -> NaCl +NaOCl + H2O

Cl2 can displace Br-/I- as Cl2 is a stronger oxidizing agent than Br2/I2.

If the organic layer turns orange-red, the solution contains Br2. If the organic layer turns purple, the organic layer contains I2.