group 7

What is the trend in melting/boiling points down the group

Increases due to increase in london dispersion forces

How does fluorine appear at room temp

Pale yellow gas

How does chlorine appear at room temp

Pale green/yellow gas

How does bromine appear at room temp

orange-brown liquid

How does iodine appear at room temp

Grey-black solid

What colour is bromine as a gas

Orange

What colour is iodine as a gas

Purple

How does chlorine appear in aqueous solution

Colourless/pale green

How does chlorine appear in organic solvents

Colourless/pale green

How does bromine appear in aqueous solution

Orange

How does bromine appear in organic solvents

Orange

How does iodine appear in aqueous solution

Yellowy-Brown

How does iodine appear in organic solvents

Purple

Why is the electronegativity of halogens significant

Halogens have high electronegativity meaning they are good oxidising agents. Going down the group, atoms get larger so it is harder to gain electrons (reactivity decreases down the group)

what is the trend in volatility down group 7

Volatility decreases down the group as molecular size increases, leading to stronger van der Waals forces.

what is the structure of halogens

exist as diatomic molecules so are simple molecular structures with weak London dispersion dories between them caused by instantaneous dipole-induced dipole forces

explain the trend in boiling point, melting point and volatility down group 7

the more electrons, the Greater London forces, therefore the larger the molecule, the stronger these forces between molecules. therefore, down the group, it gets more difficult to separate the molecules so boiling and melting points increase. it gets more difficult to separate the molecules so volatility of halogens decreases down the group.

what is the trend of electronegativity down the group

decreases down the group, therefore their oxidising power decreases going down the group.

which element in group 7 is the strongest oxidant agent

fluorine due to its high electronegativity and small atomic radius, allowing it to attract electrons more effectively than other halogens.

what is the trend in reactivity down group 7

reactivity decreases down the group due to increasing atomic size and shielding effect, making it harder for the larger atoms to attract electrons.

what is formed in the reactions between halogens and (some) metals

metal halide salts, which are ionic compounds consisting of halogen anions and metal cations.

what is happening to the metals when reacting with halogens

the metal is being oxidised, so halogens are acting as oxidising agents

how do halogens (chlorine, bromine and iodine) react with iron (II)

chlorine and bromine oxidise iron(II) to iron(III), while iodine has a lesser oxidising ability. iodine is oxidised from iodide ions to iodine

give the ionic equation of chlorine oxidising iron (II)

Cl2(g) + 2Fe2+(aq) → 2Cl-(aq) + 2Fe3+(aq)

give the ionic equation for the reaction between iodine and iron (III)

2I-(aq) + 2Fe3+(aq) → I2(aq) + 2Fe2+(aq)

give the equation for the reaction between chlorine and water

Cl2(g) + H2O(l) ↔ HCl(aq) + HOCl(aq)

give the equation for the reaction between cold sodium hydroxide and chlorine

Cl2(aq) + 2NAOH(aq) → NaCl(aq) + NaClO(aq) + H2O(l)

give the equation for the reaction between hot, concentrated sodium hydroxide and chlorine

3Cl2(aq) + 6NaOH(aq) → NaClO3(aq) + 5NaCl(aq) + 3H2O(l)

how can the reducing power of halides be compared

by reacting them with concentrated sulphuric acid

what happens when a halide ion acts as a reducing agent

it loses electrons, given to the reduced species

what is the trend in reducing power down the group

reducing power increases down the group (I>Br>Cl>F)

why is sulphuric acid used to observe the reducing power of halides

as it can be reduced to many different oxidation states

what are the 4 species and their oxidation states containing sulphur

• H2SO4 → +6

• SO2 → +4

• S → 0

• H2S → -2

what happens during the test when concentrated sulphuric acid is added to solid samples of halide salts

NaX(s) + H2SO4(l) → HX(g) + NaHSO4(aq)

• acid-base reaction. concentrated acid means there are not many water molecules to fully dissociate, only one H+ ion is lost.

• HX(g) from reaction may reduce H2SO4 as gas bubbles through acid redox reaction where concentrated sulphuric acid acts as oxidising agent

what can the hydrogen halides (HBr, HCl and HI) be observed as

steamy fumes caused by HX gas reacting with water vapour in the air to produce a fog of concentrated HX acid

give the equation for the equation between NaCl and concentrated H₂SO₄ (1)

NaCl + H₂SO₄ → NaHSO₄ +HCl

what can be observed in the reaction between Cl^- ions and concentrated sulphuric acid

steamy fumes of HCl

give the equations between NaBr (Br- ions) and concentrated sulphuric acid (2)

NaBr + H2SO4 → NaHSO4 + HBr

2Br- + H2SO4 + 2H+ → Br2 + SO2 + 2H2O

what can be observed in the reaction of br- ions with concentrated sulphuric acid

• HBr - steamy fumes

• Br2 - brown fumes

• SO2 - colourless gas

give the equations for the reaction between NaI (I- ions) and concentrated sulfuric acid (4)

• NaI + H2SO4 → NaHSO4 + HI

• 2I- + H2SO4 + 2H+ → I2 + SO2 + 2H2O

• 6I- + H2SO4 + 6H+ → 3I2 + S + 4H2O

• 8I- + H2SO4 + 8H+ → 4I2 + H2S + 4H2O

what can be observed in the reaction between I- and concentrated H2SO4

• HI - steamy fumes

• I2 - purple fumes

• SO2 - colourless gas

• S - yellow solid

• H2S - gas (bad egg smell)

Give the balanced equation of the reaction between ammonia and hydrogen chloride

NH3(g) + HCl(g) ←→ NH4Cl(s)

What can be observed in the reaction between ammonia and hydrogen chloride

White smoke