C9. Group 2, The Alkaline Earth Metals Flashcards
What are the trends for group 2?
Elements for 2+ ions when reacting; atomic radius increases down a group; Electron configuration ends in S2
What is the trend for first ionisation energy going down group 2?
Decreases; More shielding; Atomic radius increases (increase in nuclear charge but shielding overrides increase in positive charge)
What are the trends for melting points going down group 2?
Decreases; Metallic structure; Size of metal ions increase, delocalised electron unchanged, charge same; Distance between positive nuclei and delocalised electrons increase, weakens attractive forces; Less energy required to break bonds, lower melting points
What happens when reacting water with group 2 metals?
Form base; Metal hydroxide;
Sr2(s) + 2H2O(l) => Sr(OH)2(aq) + H2(g)
What are the trends in reactivity going down group 2?
Increases; Atomic radius increases, more shielding, easier to remove electron
How does Magnesium react differently with water?
Slowly reacts w/ cold water; Vigorously reacts w/ steam producing Magnesium Oxide
What are the trends in solubility for sulfates going down group 2?
If anion has double charge, less soluble going down group; Mg - very soluble, Ba - sparingly soluble
What are the trends in solubility for hydroxides going down group 2?
If anion has single charge , more soluble going down group; Mg - sparingly soluble, Ba - very soluble
How do you test for sulfates?
Add HCl to remove carbonates giving false result; Add Barium Chloride BaCl2; White precipitate if sulfate present
What is the ionic equation for neutralisation of acids?
H+(aq) + OH-(aq) => H2O(l)
What compound is used to neutralise acidic soil?
Calcium Hydroxide Ca(OH)2
What compound is used to neutralise stomach acids?
Magnesium Hydroxide Mg(OH)2
Why can we ingest barium sulfate if it is toxic?
It in insoluble, will not be absorbed by the blood
What are barium meals and what are they used for?
Barium sulfate, used to identify problems in digestive tract; Patient drinks suspension of barium sulfate, coating lining of soft tissue; X Rays absorbed by barium sulfate
How do you extract titanium?
Titanium ore, TiO2, converted to titanium (IV) chloride, TiCl4, by heating w/ C and Cl gas; Fractionally distilled to increase purity; TiCl4 reduced w/ Mg in 1000c furnace
