Topic 4 Inorganic chemistry

Going down group 2, do elements become more or less reactive?

More reactive

Trend in first ionisation energy in Group2

More easily oxidised going down Group 2

Lower 1st IE

What do Group 2 Metals react with?

• Oxygen

• Chloride

• Water

• Acids

Equation for Magnesium + Oxygen

2Mg(s) + O2(g) → 2MgO(s)

Equation for magnesium + Chlorine

Mg(s) + Cl2(g) → MgCl2

Why does beryllium not react with water?

Because it has a thick oxide layer at the surface.

Equation for Magnesium and steam

Mg(s) + H20 → MgO(s) + H2(g)

Equation for magnesium and water

Mg(s) + 2H20 → Mg(OH)2 (s) + H2 (g)

What happens when cold water is added to calcium oxide

Mixture swells, freezes and a lot of energy and water vapor is released.

Equation for Calcium oxide with water

CaO (s) + H2O (l) → Ca(OH)2 (aq)

Equation of Magnesium oxide + HCL

MgO (s) + HCl (aq) → MgCl2(aq) + H2O

Equation of Calcium oxide + Nitric acid

CaO (s) + 2HNO3 (aq) → Ca(NO3)2 (aq) +H2O

Equation of calcium hydroxide + HCl

Ca(OH)2 (s) + 2HCl (aq) → CaCl2 (aq) + 2H2O

Equation of calcium hydroxide + Nitric acid

Ca(OH)2 (s) + 2HNO3 → Ca(NO3)2 (aq) + 2H2O

What is used to test for sulfate ions

Barium chloride

Definition of thermal stability

How much energy it can absorb before it breaks down

Going down group 2, does solubility in water increase or decrease?

Decrease

What Group 2 compounds are insoluble in water

Group 2 Carbonates

Which group 2 compound is soluble in water

Group 2 nitrates

Thermal stability trend in group 2

Thermal stability increase going down group 2

Charge density trend in group 2

Decreases down group 2

Relationship between charge density, polarity power and thermal stability

Smaller charge density = Greater polarising power= increase in thermal stability

Adding silver nitrate to Chloride ions

White Precipitate formed

Adding silver nitrate to Bromide ions

Cream precipitate formed

Adding silver nitrate to Iodide ions

Yellow precipitate formed

Adding dilute aqueous ammonia to Chloride ions

soluble

Adding dilute aqueous ammonia to Bromide ions

insoluble

Adding dilute aqueous ammonia to Iodide ions

insoluble

Adding concentrated aqueous ammonia to Chloride ions

soluble

Adding concentrated aqueous ammonia to Bromide ions

soluble

Adding concentrated aqueous ammonia to Iodide ions

insoluble

Silver nitrate + Sodium chloride

AgNO3 (aq) + NaCl(aq) → AgCl(s)+ NaNO3(aq)

Acid formed when water reacts with Hydrogen fluoride

Hydrofluoric acid

HF+ H2O →← H3O+ F

Acid formed when water reacts with Hydrogen chloride

Hydrochloric acid

HCl + H2O → H3O + Cl

Acid formed when water reacts with Hydrogen bromide

Hydrobromic acid

HBr+ H2O → H3O + Br

Acid formed when water reacts with Hydrogen iodide

Hydriodic acid

HI+ H2O → H3O +I

Reaction of ammonia and hydrogen bromide

NH3 (g) + HBr(g) → NH4Br(s)

Concentrated sulfuric acid + NaCl

Observation: misty fumes

Products: HCl

Concentrated sulfuric acid + NaBr

Observation:

Misty fumes, Brown fumes, colourless gas with choking smell

Products:

HBr, Br2, SO2

Concentrated sulfuric acid + NaI

Observation:

misty fumes, purple fumes or black solid, colourless gas with choking smell, yellow solid, colourless gas with rotten egg smell

Products:

HI, I2, SO2, S, H2S

Which group 2 compounds are soluble?

• Group 2 nitrates

• Group 2 chlorides

How to test for sulfate ions

• Add barium ions

• forms a white participate

The use of thermal decomposition

Use of heat to break down a reactant into more than one product

Thermal decompostion of MgCO3

MgCO3→ MgO + CO2

Trend in thermal decomposition down group 2

Decrease down

Why do Group 2 Carbonates get more thermally stable down the group

• Cations get bigger

• Less polarising power

• Distort the electron cloud less

What is produced when Group 2 nitrates are decomposed on heating

• Group 2 oxides

• nitrogen dioxide gas

• oxygen

Trend in melting point and boiling point in Group 7

• Increase down the group due to more electrons

Trends in electronegativity in group 7

Decreases down the group

Trends in reactivity in group 7

Reactivity decreases down the group as atoms get bigger.

Observation of NaCl reacting with sulfuric acid

• misty fumes

• hydrogen chloride produced

Observation of NaBr reacting with sulfuric acid

• misty fumes

• brown fumes

• chocking smell

• Product: HBr, Br2, SO2

Observation of NaI reacting with sulfuric acid

• misty fumes

• purple fumes

• yellow solid

• Rotten smell

• Produces: HI, I2, SO2, S, H2S