2. New Way Chemistry for Hong Kong A-Level Book 1 1 Chapter 10 Metallic Bonding 10.1Metallic Bonding 10.2Metallic Radius 10.3Factors Affecting the Strength of Metallic Bonding Metallic Bonding 10.4 Metallic Crystals

3. New Way Chemistry for Hong Kong A-Level Book 1 2 The electron sea model of bonding in metals The structure of metal consists of a giant structure of cationic lattice immersed in a sea of mobile valence electrons. The electrostatic attraction between the delocalized electron cloud and the metallic ions is the metallic bonding. 10.1 Metallic Bonding (SB p.248)

4. New Way Chemistry for Hong Kong A-Level Book 1 3 Metallic radius (r) is defined as half of the internuclear distance between atoms in a metal crystal. 10.2 Metallic Radius (SB p.249) Atoms in a metallic crystal

5. New Way Chemistry for Hong Kong A-Level Book 1 4 The metallic bond increases with: 1. decreasing size of the metal atom (i.e. the atomic/metallic radius); 2. increasing number of valence electrons of the metal atom. 10.3 Factors Affecting the Strength of Metallic Bonding (SB p.249) Metals with small and highly charged cations form stronger metallic bonds

6. New Way Chemistry for Hong Kong A-Level Book 1 5 10.3 Factors Affecting the Strength of Metallic Bonding (SB p.250) Effect of number of valence electrons on metallic bond strength MetalNumber of valence electrons(s)Melting point ( o C) Sodium Magnesium Aluminium 123123 98 650 660

7. New Way Chemistry for Hong Kong A-Level Book 1 6 10.3 Factors Affecting the Strength of Metallic Bonding (SB p.250) Effect of metallic radius on metallic bond strength of Group 1A metals MetalMetallic radius (mm)Melting point ( o C) Lithium Sodium Potassium Rubidium Caesium 0.152 0.186 0.231 0.244 0.262 180 98 64 39 29

8. New Way Chemistry for Hong Kong A-Level Book 1 7 Closed-packed Structure 10.4 Metallic Crystals (SB p.250)

9. New Way Chemistry for Hong Kong A-Level Book 1 8 (a) normal side view (b) exploded view (c) a unit cell Co-ordination no. = ? Empty space = 26% 10.4 Metallic Crystals (SB p.252) Hexagonal close-packed structure

10. New Way Chemistry for Hong Kong A-Level Book 1 9 (a) normal side view (b) exploded view (c) a unit cell Co-ordination no. = ? Empty space = 26% 10.4 Metallic Crystals (SB p.252) Cubic close-packed / Face-centred cubic structure

11. New Way Chemistry for Hong Kong A-Level Book 1 10 Open Structure 10.4 Metallic Crystals (SB p.253)

12. New Way Chemistry for Hong Kong A-Level Book 1 11 (a) normal side view (b) exploded view (c) a unit cell Empty space = 32% 10.4 Metallic Crystals (SB p.253) Body-centred cubic structure

13. New Way Chemistry for Hong Kong A-Level Book 1 12 The crystal structures of the solid metal elements 10.4 Metallic Crystals (SB p.254)

14. New Way Chemistry for Hong Kong A-Level Book 1 13 The END