BONDING IN METALS Section 4 Chapter 5
Metals & Alloys Alloys- a mixture of two or more elements, at least 1 is a metal. Most of the objects we see and use are made of alloys. Alloys are mixtures and not compounds. Why is an alloy NOT a compound? Because the metals in the alloy do not react chemically.
Positive ions surrounded by loose valence electrons. Metallic Bonding Remember, most metals have 1, 2, or 3 valence electrons. During the chemical bonds metal atoms usually lose electrons becoming positively charged. What type of bond forms when valence electrons are lost or gained by other atoms resulting in a positive or negative charge? Positive ions surrounded by loose valence electrons.
Examples of Aluminum Foil When an element has only one, two or three valence electrons, the bond between these electrons and the nucleus is relatively weak. So, for example, when aluminum atoms are grouped together in a block of metal, the outer electrons leave individual atoms to become part of common “electron cloud.” In this arrangement, the valence electrons have considerable mobility and are able to conduct heat and electricity easily. Also, the nature of the bonds, make it possible for the atoms to slide past each other when the metal is deformed instead of fracturing like glass or other brittle material. Examples of Aluminum Foil
Properties of metals include: Electrons and ions in metals can move, so metals are flexible and can conduct heat and electricity. Properties of metals include: Luster: Basically a reflective nature or “shininess” Malleability: Flattened, shaped, and pounded metal. Ductility: metals can be bent and pulled into thin strands. Electrical Conductivity: Current moves freely between electrons. Thermal Conductivity: Again, because the electrons move freely, metals conduct heat very well.
Luster
Malleability
Ductility
Aluminum Foil Project Create a relief of your face! You will create an original sculpture, or relief using any type of metal. You can ONLY use metal except for the base. The main project must use aluminum foil with metal nuts, bolts, wire, colored foil or anything metal added to it. If you create a sculpture, it must have a base. You can use cardboard, wood or a small plate. Be sure the sculpture is secured to the base. No taller than 12”s
Aluminum Foil Projects