Inorganic Chemistry | Group 17

melting and boiling points

melting and boiling points

• increase

• molecule size increase

• number of electrons increase, stronger van der waals forces

radii

increase

new shell added

E.N.

decrease, electrons added and shielding increases

colour

• F - yellow

• Cl - yellow brown

• Br - red-brown / yellow

• I - grey black

• At - black

reaction with H₂

halogen + hydrogen = halide

F = explosion and Cl = vigorous

Thermal stability

heated HF adn HCl not decomposed but HI does = purple gas

strength of halide bond decreases

1. Hydrogen Halides: Their thermal stability decreases as you go down the group. So, HF is more thermally stable than HI. The lower halides (like HI) break down more easily with heat.

2. Diatomic Halogens: Their thermal stability also decreases down the group. F2​ is more thermally stable than I2​, meaning I2​ is easier to break apart than F2​.

reaction of silver ions and ammonia

• AgF - colourless

• AgCl - white

• AgBr - cream

• AgI - yellow

reaction with sulfuric acid

cold and solid

hydrogen halide given

NaCl + H2SO4 ⟶ HCl + NaHSO4

limited to an acid-base reaction

• NaF and NaCl: Only release HF and HCl gases, respectively.

• NaBr: Primarily forms HBr gas, with possible traces of Br2​ and SO2​.

• NaI: Forms HI gas, along with some I2​, SO2​, and possibly even S.

reaction with H2SO4

if oxidising agent

HBr + H2SO4 ⟶ H2O+ Br2 + O2

not strong enough for F and Cl

Cl reaction with NaOH

redox and disproportionation reaction

cl is both oxidised and reduces at the same time

cold: Cl2 + NaOH ⟶ NaCl + NaClO + H2O

hot: 3Cl2 + 6NaOH ⟶ 5NaCl + NaClO3 + 3H2O

chlorination: Cl + H2O ⟶ OCl^– + HOCl