Metallic Bonds and Properties of Metals 8.4

Metallic Bonds (words to remember) A metallic bond is the attraction of a metallic cation for delocalized electrons. Delocalized electrons are electrons that are free to move around. The electron sea model proposes that all metal atoms in a metallic solid contribute their valence electrons to form a “sea” of electrons.

Properties of Metals Melting points (vary greatly) Ex: Mercury- liquid at room temp. Tungsten- melting point of 3422˚C Does not take a lot of energy to reach melting point, so atoms can move past each other Takes a lot of energy to boil because atoms are becoming a gas so cations and electrons must separate.

Malleable and ductile (and durable) Metals can be hammered into sheets and drawn into wire cations and electrons Metal is Deformed

Good Conductors Delocalized electrons are free to move, so they can move heat from one place to another very quickly. Mobile electrons can move easily in an electrical current when electricity is applied to a metal. These delocalized electrons also interact with light, absorbing and releasing photons, which gives them luster.

Strength and Hardness Mobile electrons in transition metals consist of not only two outer s electrons but also inner d electrons. As the number of delocalized electrons increases so do hardness and strength. Ex: Chromium, iron, and nickel have strong metallic bonds Alkali metals are considered soft because they only have one delocalized electron.