Chemical bonds - CHEM 1101: CHEMISTRY (EEE/COE) LECTURE 5...

Info iconThis preview shows pages 1–3. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: CHEM 1101: CHEMISTRY (EEE/COE) LECTURE 5 INTRODUCTION TO CHEMICAL BONDS CHEMICAL BOND Definition : A chemical bond is defined as a force that acts between two or more atoms to hold them together as a stable molecule. Main types of bond : 1. Ionic or electrovalent bond, 2. Covalent bond, 3. Coordinate covalent bond Forth type of bond : Metallic bond: The type of bonding which holds the atoms together in metal crystal. Valence electron : The electrons in the outer most energy level in an atom that takes part in chemical bonding are called valence electrons. Bonding electrons : The valence electrons actually involved in bond formation are called bonding electrons. Octet rule : In chemical bond formation, atoms interact- (i) by losing, (ii) by gaining or (iii) by sharing electrons to acquire a stable noble gas configuration. He (2) 2 Ne (10) 2, 8 Ar (18) 2, 8, 8 Kr (36) 2, 8, 18, 8 Xe (54) 2, 8, 18, 18, 8 Rn (86) 2, 8, 18, 32, 18, 8 The tendency for atoms to have eight electrons in the outer shell is known as Octet rule. IONIC BOND Definition : The electrostatic attraction between the cation (+ve ions) and anions (-ve ions) produced by electron transfer constitutes an ionic or electrovalent bond. Conditions for formation of ionic bond : (1) Bond formations occur between the metal and nonmetal. Metal is donor and nonmetal is acceptor. (2) Net lowering of energy: AIUB Updated:25/09/2010 Course-Teacher: Shahrina Alam 1 A B : .. . . . B _ A + 1 valence electron 7 electron valence (cation) (anion) A + B _ A + B _ A B or A + B _ ( ) ionic bond CHEM 1101: CHEMISTRY (EEE/COE) LECTURE 5 To form a stable ionic compound, there must be a net lowering of the energy. For example- formation of NaCl molecule (a) Na e Na + 119 kcal (b) Cl + e Cl +85 kcal (c) Na + + Cl Na + Cl +187 kcal Net energy released, 187 + 85 119 = 153 kcal...
View Full Document

This note was uploaded on 04/16/2011 for the course EEE 30 taught by Professor Dr.sohrabuddin during the Spring '11 term at American Intl. University.

Page1 / 6

Chemical bonds - CHEM 1101: CHEMISTRY (EEE/COE) LECTURE 5...

This preview shows document pages 1 - 3. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online