Metal ions with large positive charge and small size may acidify solution

>> YOUR LINK HERE: ___ http://youtube.com/watch?v=71DHy5vqtbA

𝗟𝗘𝗔𝗥𝗡𝗜𝗡𝗚 𝗢𝗕𝗝𝗘𝗖𝗧𝗜𝗩𝗘 • ♥ Predict the acid/base properties of ionic compounds. • NOTE • It is not practical to memorize the exact list of acidic metal ions. In Jonathan’s chemistry course, let’s call the following ions acidic in water via metal ion hydrolysis: • ♥ Be²⁺(aq) • ♥ Al³⁺(aq) • ♥ Aqueous transition metal ions with 2+ and 3+ charge • Cations from Group 1 and Group 2 (other than Be²⁺) are neutral in water. • MORE INFORMATION • The quantity of coordinating (attached to) water molecules is dependent on the size of the cation. Larger cations are coordinated by more water molecules than smaller cations. For instance, the relative ionic radii are Be²⁺ (small) ‹ Mg²⁺ ‹ Ca²⁺ (large), and the number of coordinating water molecules is Be²⁺ (four H₂O) ‹ Mg²⁺ (six H₂O) ‹ Ca²⁺ (eight H₂O). In the video, the number of coordinating water molecules is obtained from Persson (2010, 2022) and Gilson and Durrant (2009). • Information about ionic size and acidity (p𝘒ₐ) are found in Contakes and Gilson and Durrant (2009). • TRANSCRIPT • In aqueous solution, soluble metal ions are surrounded by a layer of water molecules. Small metal ions with large positive charge, 2+ or 3+, may have enough charge density to split apart water molecules. The metal ion’s intense positive charge pulls electrons from a water molecule such that the water molecule splits apart. The OH⁻ part of water is stuck electrostatically to the metal ion. The H⁺ part of water is released into solution and makes the solution acidic. • Beryllium ion and aluminium ion are small and have much positive charge to split water. Several transition metal ions with 2+ or 3+ charge are also small enough to split water. • On the contrary, ions from Group 1 and most of Group 2 have low positive charge, 1+, and/or large size. These ions can be surrounded by a layer of water molecules but do not have the intense charge density to split water. These ions do 𝗻𝗼𝘁 make the solution acidic. • Original content © 2024 Jung-Lynn Jonathan Yang • ♥ • REFERENCES • Contakes SM 6.3.8: High Charge-to-Size Ratio Metal Ions Act as Brønsted Acids in Water. LibreTexts Chemistry. https://chem.libretexts.org/Bookshelv... • Gilson R, Durrant MC (2009) Estimation of the pKa values of water ligands in transition metal complexes using density functional theory with polarized continuum model solvent corrections. Dalton Transactions 2009:10223–10230. • Persson I (2010) Hydrated metal ions in aqueous solution: How regular are their structures? Pure and Applied Chemistry 82(10):1901–1917. • Persson I (2022) Structures of Hydrated Metal Ions in Solid State and Aqueous Solution. Liquids 2:210–242. • ATTRIBUTIONS • Sound effect modified from freesound.org • “Bell ding” by jmayoff • Background image modified from Unsplash • “MS9Tnh3if1o.jpg” by kiwihug

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