Chapter04 - Applied Science Department (ASD) Centre for...

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PCE 0015 Chemistry for Engineers Foundation in Engineering ONLINE NOTES Chapter 4 CHEMICAL BONDING FOSEE , MULTIMEDIA UNIVERSITY (436821-T) MELAKA CAMPUS, JALAN AYER KEROH LAMA, 75450 MELAKA, MALAYSIA. Tel 606 252 3594 Fax 606 231 8799 URL: http://fosee.mmu.edu.my/~asd/ Applied Science Department (ASD) Centre for Foundation Studies and Extension Education (FOSEE)
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PCE0015 Chemistry For Engineers Chapter 4 4.1 Lewis Dot Symbols 4.2 The Ionic Bond 4.3 The Covalent Bond 4.4 Writing Lewis Structures 4.5 Exception to the Octet Rule 4.6 The hydrogen Bond Upon completion of this chapter, you should be able to : 1. Apply Lewis dot symbols. A Lewis dot symbol shows the number of valence electrons possesses by an atom of a given element. They are useful mainly for representative elements. 2. Explain the ionic bond. An ionic bond is the product of the electrostatic forces of attraction between positive and negative ions. An ionic compound consists of a large network of ions in which positive and negative charges are balanced. 3. Explain the covalent bond. In a covalent bond, two electrons (one pair) are shared by two atoms. In multiple covalent bond, two or three pairs of electrons are shared by two atoms. 4. Write Lewis structure. The arrangement of bonding electrons and lone pairs around atoms in a molecule is represented by a Lewis structure. 5. Understand and apply the octet rule. The octet rule predicts that atoms form enough covalent bonds to surround themselves with eight electrons each. There are exceptions to the octet rule. 6. Explain the hydrogen bond. Hydrogen bond is a special type of dipole-dipole interaction (attraction between polar molecule) between the hydrogen atom in a polar bond, such as N H, O H, or F H, and an electronegative O, N, or F atom. __________________________________________________________________________________ HST/MAM 2/ 8
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PCE0015 Chemistry For Engineers Chapter 4 4.1 LEWIS DOT SYMBOLS Lewis dot symbol consists of the symbol of an element and one dot for each valence electron in an atom of the element . Figure below shows the Lewis dot symbols for the representative elements and the noble gases. Note that except for helium, the number of valence electrons each has is the same as the group number of the element. Elements in the same group have similar outer electron configurations and hence similar Lewis dot symbols. 4.2 THE IONIC BOND An ionic bond is the electrostatic force that holds ions together in an ionic compound . For example, the reaction between lithium and fluorine to form lithium fluoride. The electron configuration of lithium is 1 s 2 2 s 1 , and that of fluorine is 1 s 2 2 s 2 2 p 5 . When lithium and fluorine atoms come in contact with each other, the outer 2 s 1 valence electron of lithium is transferred to the fluorine atom. Using Lewis dot symbols, the reaction
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This note was uploaded on 04/10/2010 for the course CHM CHM101 taught by Professor Woljaong during the Fall '07 term at Multimedia University, Cyberjaya.

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Chapter04 - Applied Science Department (ASD) Centre for...

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