inorganic chem; group 2 Flashcards
What happens to atomic radius down the group?
Increases
What happens to IE down group 2?
Decreases
Explain the IE trend down group 2
- Atomic size increases
- More shielding — weaker attraction between nucleus & outer e-
- Both these factors make removing the e- easier which decreases IE
What happens to melting points down Group 2?
Generally decreases down the group
Group 2 structure
Forms metallic structures — +ve metal ions attracted to a sea of delocalised e-
Explain melting point trend down Group 2
- Size of metal ion increases, but no.of delocalised e- & charge stays the same
- Distance between nucleus & e- increases — weakens attractive force
- Easier to break bonds, less energy required to remove e- — lowers melting points
What element is the exception of melting point trend & why
Mg
Due to structural differences
Group 2 elements react with water to form…
Bases (metal hydroxides)
What is the reactivity trend in Group 2?
Increases with water
Be (no reaction) — Ba (very reactive)
Explain reactivity trend in Group 2?
- Atomic size increases — e- further from nucleus
- Shielding increases
- Easier to remove e- (hence more reactive)
Magnesium reaction with water…
- Mg reacts slowly with cold water
- Mg reacts more vigorously with steam — produces MgO (magnesium oxide) instead of a hydroxide
What is the solubility trend of Group 2 compounds?
Group 2 hydroxides & surfaces have opposite solubility down the group
Table of Group 2 hydroxides & sulaftes…
Rule of Group 2 sulfates solubility…
If the anion (-ve ion) has a double charge they become less soluble down the group
Rule of Group 2 hydroxides solubility…
If the anion (-ve ion) has a single charge they come more soluble down the group
Test for Sulfates
- Add HCl to remove any carbonates — these could precipitate out after adding barium chloride (giving false result)
- Add barium chloride
+ve result: white precipitate
Group 2 compounds can be used to neutralise…
Acids
What neutralises acidic soils?
Ca(OH)2 — calcium hydroxide
What neutralises antacids (stomach acid)?
Mg(OH)2 — magnesium hydroxide
Ionic equation for neutralisation
H⁺(aq) + OH⁻(aq) → H₂O(l)
What is barium sulfate used for?
Identifies problems with the digestive tract — x-rays are absorbed by barium sulfate so tissue can show on x-ray
Why is barium sulfate used?
As barium compounds are toxic, barium sulfate is insoluble so it cannot be absorbed into the blood
What is used to extract titanium?
Mg
Process of extracting titanium
- Titanium ore (TiO2) is converted to titanium IV chloride (TiCl4) — by heating with carbon & chlorine gas
- Titanium IV chloride is passed through a fractional distillation column to increase the purity
- The purified TiCl4 is reduced using Mg in 1000˚C furnace
Equation for extracting titanium
TiCl4 + 2Mg → Ti + 2MgCl2
What is used to remove sulfur dioxide emissions
Calcium carbonate & oxide
What is the process used to remove sulfur dioxide emissions?
Wet scrubbing — it’s a method where an alkali is used to neutralise sulfur dioxide in flue gases
Explain the process of wet scrubbing & its product
Involves dissolving calcium carbonate/oxide in water & spraying on acidic sulfur dioxide gas
Product — calcium sulfite
