AS Inorganic Chemistry

What is the trend in electronegativity going down group 7?

• Decreases going down the group

• Atomic radius increases and sheilding increases

• Electrostatic attraction decreases so it becomes harder to attract an electron

What is the trend in boiling point going down group 7?

• Increases going down the grouo

• Group 7 are simple molecules with only Van der Waals forces

• Atomic radius increases, so more VDW

• More energy requires to overcome these forces

What is the trend in oxidising ability going down group 7?

Decreases as electronegativity decreases

What is the trend in reducing ability going down group 7?

• Increases going down the group

• Atomic radius and shielding increase

• Weaker electrostatic attraction

• So electrons are released more easily

How do solid sodium halides react with concentrated H₂SO₄ and what is the equation?

X^-(aq) + H₂SO₄(l) → HCl(g) + HSO₄ ^- (aq)

• Chlorine: white gas

• Bromine

What precautions are needed to be taken when reacting solid sodium halides with concentrated H₂SO₄?

Toxic gases produced so experiment must be carried out in a fume cupboard

How are halide ions tested for and what are the results?

• Add nitric acid and then silver nitrate

• Cl- = white ppt

• Br- = cream ppt

• I- = yellow ppt

Why is silver nitrate solution used to identify halide ions?

Ag- ions react with halide ions to form a precipitate with a distinct colour

Why is the silver nitrate solution acidified when identifying halide ions?

To prevent interference from other ions that could also form precipitates with silver ions

Why is ammonia solution added when identifying halide ions, and what are the results of adding NH₃?

Helps distinguish ions as colours are hard to tell apart

• Cl: dissolves in both dilute and conc NH₃

• Br: dissolves in only conc NH₃

• I: dissolves in neither dilute or conc NH₃

What are the equations of halogens reacting with concentrated H₂SO₄?

• H₂SO₄ (l) + NaCl(s) → HCl (g) + NaHSO₄

• H₂SO₄ (l) + NaBr(s) → HBr(g) + NaHSO₄

• H₂SO₄ (l) + NaI(s) → HI (g) + NaHSO₄

What is the reaction of chlorine and water?

Cl₂(aq) + H₂O(l) → HCl(aq) +HClO(g)

What is chlorine used for?

Sterilising agent

What is the reaction of chlorine and water in sunlight?

2Cl₂(aq) + H₂O(l) → 4HCl(aq) +O₂(g)

What is the reaction of chlorine with sodium hydroxide?

Cl₂(g) + 2NaOH(aq) → NaCl(aq) + NaClO(aq) + 2H₂O(l)

What is the product of the reaction of chlorine with sodium hydroxide used for?

bleach as a disinfectant

What is the trend in atomic radius going down group 2?

• Increases down the group

• Extra shells are being added so the size of the molecule is increasing

What is the trend in first ionisation energy going down group 2?

• Decreases down the group

• Nuclear charge increases

• Shielding and atomic radius increases

• Electrostatic attraction decreases

• So less energy required to remove outer electron

What is the trend in melting/boiling point going down group 2?

• Decreases going down the group

• Atomic radius and size of molecule increases

• Shielding increases

• Metallic bonds are weaker

• So less energy required to break bonds

How reactive are the or group 2 metals with water?

• Mg: only reacts with steam

• Ca: vigorously reacts

• Sr: vigorously reacts

• Ba: vigorously reacts

What are the equations for group 2 metals with water?

• Mg(s) + H₂O(g) → MgO(s) + H₂(g)

• Ca(s) + 2H₂O(l) → Ca(OH)₂(s) + H₂(g)

• Sr(s) + 2H₂O(l) → Sr(OH)₂(s) + H₂(g)

• Ba(s) + 2H₂O(l) → Ba(OH)₂(s) + H₂(g)

What is the trend in solubility of metal hydroxides going down group 2?

• Increases going down the group

• Mg(OH)₂ is sparingly soluble

• Ba(OH)₂ is soluble

What is the trend in solubility of metal sulfates going down group 2?

Decreases going down the group

What is the equation for group 2 hydroxides being dissolved?

X(OH)₂ (aq) → X²⁺ (aq) + 2OH^- (aq)

What is the equation for group 2 sulfates being dissolved?

XSO₄ (s) → X²⁺ (aq) + 2SO₄^2- (aq)

What is Mg used for, and what is its equation?

• Extracting titanium from its core

• 2Mg + TiCl₄ → 2MgCl₂ + Ti

What is Mg(OH)₂ used for, and what is its equation?

• Neutralising stomach acid and treating constipation

• Mg(OH)₂ (s) + 2HCL(aq) → MgCl2 (aq) + 2H₂O (l)

What is Ca(OH)₂ used for?

raising pH of soil

What is CaO/CaCO₃ used for, and what is its equation?

sulfur scrubbing

What is BaSO₄ used for?

Barium meal that absorbs X-Rays

What is BaCl₂ used for?

• Testing for sulfate ions

• Produces a white ppt

• Acidified to remove any carbonates that may be present and produce a ppt

What is the trend in atomic radius going across period 3?

• Decreases across period

• Proton number and nuclear charge increases

• Shielding remains constant

• Electrostatic attraction increases so electrons are pulled further to the nucleus

What is the trend in first ionisation energy going across period 3?

• Increases across the period

• Nuclear charge increases

• Atomic radius decreases

• Electrostatic increases between nucleus and electrons, spo more energy is required for forces to be overcp,e

• Al is lower than Mg as the 3p orbital has a higher energy and is easier remove an electron from than the 3s orbital from Mg

• Si is lower than P as there is 2 electrons in 3p orbital of sulfur so they repel stronger so it is easier to remove an electron from the 3p orbital of P as electrons are unpaired

What are the exceptions to the trend in first ionisation energy going across group 3?

• Al is lower than Mg as the 3p orbital has a higher energy and is easier remove an electron from than the 3s orbital from Mg

• Si is lower than P as there is 2 electrons in 3p orbital of sulfur so they repel stronger so it is easier to remove an electron from the 3p orbital of P as electrons are unpaired

What is the trend in melting/boiling point going across period 3?

• Increases and then decreases across period

• Na → Al haas metallic bonds

• Al donates the most electrons so bonding is strongest

• Si is a giant covalent and has 4 bonds per atom so is the strongest

• P-Ar exist as simple molecules and only have VDW so little energy required to overcome