NYJC Chemical Bonding Revision for term III pdf

NYJC Chemical Bonding Revision for term III pdf - H2...

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H2 Chemistry 2011 term 3 Revision Chemical Bonding Nanyang JuniorCollege Section A (Questions to be discussed on 19 July 2011) One of the important things about chemical bonding is the ability to recognise the structure and bonding in a given compound. Please test your self by fill in the blanks. 1) Properties Structure Bonding strength *Particles involved in bonding (be specific to the question) Bonds broken during melting and bonding Examples Volatility i.e. mp, bp, (state low or high) Conduc- tivity (State yes or no and in which state) Solubili-ty (state solubility in polar or non-polar solvents) a (Giant) ionic Ionic strong Between *cations and *anions Compds from Gp1 or 2 metals and Gp 6 or 7 nonmetals e.g. NaCl, MgO etc Low i.e. high mp, bp; are solids Good conductor s in the liquid and aqueous states Soluble in polar solvents b (Giant) metallic Metallic strong Lattice of *cations and MOBILE electrons In and between metals (Gp 1,2, 3, 4 or transition metals) e.g. Na, K, Mg Cu, etc Low i.e. high mp, bp; are solids Good conductor s in the solid and liquid states Insoluble in all solvents c Macromol ecular (giant molecular) Covalent strong *atoms diamond , graphite, Si, SiO 2 Low i.e. high mp, bp, are solids Poor conductor s in all states Insoluble in all solvents d Intramolecular = very strong covalent strong Intermolecular= relatively weak Generally volatile i.e. low mp, bp volatile liquids or solids Poor conductor s in all states Soluble in non-polar solvents (Simple) molecular (DON”T use the term ‘simple covalent)” H Molecules which contains H attached to F,O or N e.g. H 2 O pd polar molecules e.g. CHCl 3 vd w non-polar molecules e.g. CH 4
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H2 Chemistry 2011 term 3 Revision Chemical Bonding Nanyang JuniorCollege 2) Can you test yourself by giving examples of polar and non-polar molecules and we will discuss it during lecture. ACJC P3 2010 3 (a) Some data on three nitrogen-containing compounds are given in the table below: Compound Molecular formula Boiling point/ oC Dinitrogen pentoxide N 2 O 5 decomposes nitric acid HNO 3 83 nitrosyl chloride NOCl -6.4 (i) Draw diagrams to illustrate the shapes of N 2 O 5 (a symmetrical molecule) and NOCl. Indicate the relevant bond angles in each case. (ii) Explain the difference in the boiling points of HNO 3 and NOCl in terms of structure and bonding. [6] ACJC P2 2010 4 Insulin is the hormone essential for carbohydrate metabolism. Partial hydrolysis of insulin gives the following tripeptide (CH 3 ) 2 CHCH(NH 2 )CONHCHCONHCH(CH 3 )CO 2 H CH 2 CH 2 CO 2 H (iii) How would you expect the melting point and the solubility in water, of an unionized covalent form of the amino acid to compare with the actual properties of the zwitterionic form? Explain. CJC P3 2010 5(e) Oil spills are a waste of valuable resources and cause environmental problems.Traditional sorbent materials also absorb water in addition to oil, and as a result are unable to stay afloat. However, a new sorbent material called ‘hydrophobic aerogels’ has been developed to solve this problem. Due to its
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NYJC Chemical Bonding Revision for term III pdf - H2...

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