1. Ch. 7.3 Bonding in Metals CHM 1

2. Metallic Bonds and properties Metals are made up of closely packed cations and free floating valence electrons –Sea of electrons model

3. Metallic Bonds and properties Properties of metals –Good conductors of electrical current –Ductile –malleable

4. Crystalline structure of metals Metals are crystalline in structure –Compact and orderly in form –3 structrual types Body-centered –Each atom has 8 neighbors (except surface atoms) Face-centered –Each atom has 12 neighbors Hexagonal-close packed –Each atom has 12 neighbors

5. Alloys Very few objects are pure metals! Alloy = a mixture composed of 2 or more elements –Important because their properties are superior –Ex. Brass = copper + zinc Harder than copper More easily cast –Steel alloys important in today’s society

6. Alloys 2 types –Substitutional Atoms are similar in size Replace one another within their corresponding crystals –Interstitial Different sized atoms Smaller atoms fit in spaces between the larger ones

7. Ionic Bonds Review Video: http://www.learner.org/vod/vod_window.ht ml?pid=800 http://www.learner.org/vod/vod_window.ht ml?pid=800