CH12 - 12: THE GROUP 2 ELEMENTS: ALKALINE EARTH METALS: Be,...

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12: THE GROUP 2 ELEMENTS: ALKALINE EARTH METALS: Be, Mg, Ca, Sr, Ba, Ra THE ELEMENTS Be in nature = mineral beryl, Be 3 Al 2 (SiO 3 ) 6 —gemstone emerald Al 3+ replaced by Cr 3+ Be 3 Al 2 (SiO 3 ) 6 + Na 2 SiF 6 + heat BeF 2 BeF2 + Mg Be Mg extracted = seawater; mineral dolomite, CaCO 3 ▪MgCO 3 ; and magnesite, MgCO 3 Ca occurs as carbonate = limestone, marble, chalk, biominerals (shells, coral) Ca, Sr, Ba extracted = electrolysis of their molten chlorides Ra extracted = uranium-bearing minerals = radioactive Group 2 vs Group 1 period trends: ↑hardness ↑MP ↑metallic bonding ↑#e- available ↓radius ↑density ↑IE Group 2 group trends: ↑radius ↓IE = ↓standard potentials M 2+ /M couple (more negative down the group) ↑reactivity ↑electropositive = easier to form +2 ions Ca, Sr, Ba, Ra react readily with cold water Mg react hot water: M(s) + 2H 2 O(l) M(OH) 2 (aq) + H 2 (g) Be, Mg, Ca, Sr hexagonal closed-packed structure Ba, Ra body-centered cubic structure
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This note was uploaded on 11/08/2011 for the course CHEMISTRY 371 taught by Professor Biokess during the Fall '08 term at Rutgers.

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CH12 - 12: THE GROUP 2 ELEMENTS: ALKALINE EARTH METALS: Be,...

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