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I onic compounds

I onic compounds. NaCl. CaCO 3. Sodium chloride ( NaCl ) lattice. This structure is known as a giant lattice , as the arrangement of billions of sodium and chloride ions continues in all directions , right to the edge of the crystal.

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I onic compounds

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  1. Ionic compounds DIS-E.Casazza

  2. NaCl DIS-E.Casazza

  3. CaCO3 DIS-E.Casazza

  4. Sodium chloride (NaCl) lattice This structure is known as a giant lattice, as the arrangement of billions of sodium and chloride ions continues in all directions, right to the edge of the crystal Strong electrostatic forces of attraction hold each ion in its place. These forces are known as ionic bonding. DIS-E.Casazza

  5. DIS-E.Casazza

  6. PropertiesofIonicCompounds High melting points and boiling points (low volatility).A large amount of energy is needed to overcome the electrostatic force between oppositely charged ions for melting or boiling.Many ionic compounds have melting points greater than 500C and all are solids at room temperature. Note : Ionic bond strength is proportional to the ionic charge/sizeUse as refractory materials (heat resistant) e.g. MgO used to line the interior of blast furnaces e.g. Al2O3 used to make crucibles and spark plugs for motorcars. http://chewtychem.wiki.hci.edu.sg/Properties+of+Ionic+Compounds DIS-E.Casazza

  7. 2. Usually soluble in water (a polar solvent) but insoluble in non-polar solvents.However, not all salts (which are ionic in nature) are soluble in water. Recall what are the salts that are insoluble in water. DIS-E.Casazza

  8. 3. Conduct electrical current in molten or solution (aqueous) state but not in the solid state.In the solid state, the ions are held in fixed positions and cannot act as mobile charge carriers. In the molten or aqueous state, the electrostatic forces are overcome and the ions become mobile.In conducting electricity, the molten or aqueous ionic compounds are decomposed by the electric current – electrolysis.Note : A few non-ionic substances react with water to form mobile ions e.g. PCl3 and HCl DIS-E.Casazza

  9. 4. Hard and brittle A slight displacement along a cleavage plane by a sharp hard blow brings ions of like charges opposite one another. Strong attraction between planesbecomes strong repulsion and the ionic crystal shatters. DIS-E.Casazza

  10. Solubility The following are general rules which describe the solubility of common types of compounds in water: 1 All common sodium, potassium and ammonium salts are soluble. e.g. NaCl, K2SO4, NH4NO3 2 All nitrate salts are soluble. e.g. NaNO3, Mg(NO3)2, Al(NO3)3, NH4NO3 . 3 Common chloride salts are soluble except those of silver and lead. e.g. soluble: KCl, CaCl2, AlCl3insoluble: AgCl, PbCl2 . 4 Common sulfates are soluble except those of lead, barium and calcium. e.g. soluble: Na2SO4, MgSO4, Al2(SO4)3 insoluble: PbSO4, BaSO4, CaSO4 is slightly soluble. 5 Common oxides, hydroxides and carbonates are usually insoluble (except those of the Group 1 alkali metals (sodium, potassium, etc.) and ammonium. e.g. soluble: K2O, KOH, NaOH, NH4OH [actually NH3(aq)], Na2CO3, (NH4)2CO3 insoluble: MgO, CuO, ZnO, Mg(OH)2, Fe(OH)2, Cu(OH)2, CuCO3, ZnCO3, CaCO3 DIS-E.Casazza

  11. Precipitationreactions Precipitation Reactions occur when cations and anions of aqueous solutions combine to form an insoluble ionic solid, called a precipitate. Whether or not such a reaction occurs can be determined by using the solubility rules for common ionic solids.. DIS-E.Casazza

  12. Precipitates are insoluble ionic solid products of a reaction, in which certain cations and anions combine in an aqueous solution. The determining factors of the formation of a precipitate can vary. Some reactions depend on temperature, such as solutions used for buffers, while others are dependent only on solution concentration. The solids produced in precipitate reactions are crystalline solids. This solid can be suspended throughout the liquid or fall to the bottom of the solution. The fluid that remains is called the supernatant liquid. The two parts (precipitate and supernate) can be separated by various methods, such as filtration, centrifuging, or decanting. DIS-E.Casazza

  13. Precipitation and Double Replacement Reactions A double replacement reaction occurs when two ionic reactants dissociate and bond with the respective anion or cation from the other reactant. This can be thought of as "switching partners," that is, the two reactants "lose" their partner and form a bond with a different partner: An example of a precipitation reaction is as follows: CdSO4(aq) + K2S(aq) →  CdS(s) + K2SO4(aq) DIS-E.Casazza

  14. Hard water http://www.homecents.com/h2o/h2o_soft/index.html DIS-E.Casazza

  15. When it hits the ground, rain interacts with vegetation, top soil, and bedrock, dissolving whatever is soluble and finally ends up in our lakes, rivers, streams and ground water. Of the soluble minerals calcium, magnesium and iron are three that can make our water “hard.” Hard water causes soaps and detergents to lose some effectiveness. The mineral salts react with soap to form an insoluble mix that can lead to coagulated curd and a film or scum. Zeolites are minerals that are microporous cage-like molecules. Theses cages are interconnected forming a framework with many cavities and channels. The zeolite pictured here is the main ingredient in a water softener device. The process is called “ion-exchange”. The zeolite/resin carries a negative charge and the offending minerals carry a positive charge. The positive charged mineral ions exchange places with the weaker positively charged sodium ions and are held fast in the zeolite until they themselves are knocked off during the recharge cycle. After recharging, the zeolite is cleaned of the bad minerals and reunited with its slightly positive friend the sodium ion and ready to attract more minerals in the water stream. The essential part of a water softener is the mineral tank that holds the negatively charged resin/zeolite beads. Calcium, magnesium and sodium (the minerals that make your water hard) carry positive charges with sodium holding the weaker charge of the three. DIS-E.Casazza

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