Ionic and Metallic Compounds

Ionic and Metallic Compounds

by Jennifer Haycraft

​Ionic Compounds

​The electrostatic force that holds oppositely charged particles together in an ionic compound is an ionic bond.

​Compounds that contain ionic bonds are called ionic compounds.

​Properties of Ionic Cmpds

​Strong attractions among the positive ions and negative ions in an ionic compound result in the formation of a crystal lattice.

​A crystal lattice is a 3-D geometric arrangement of particles. Each positive ion is surrounded by negative ions and each negative ion is surrounded by positive ions

​Physical Properties

​High melting & boiling points

​Hard yet brittle

​Does not conduct electricity in the solid state.

​However, ionic compounds are excellent conductors, known as electrolytes, in the liquid or aqueous (dissolved in water) states

​Lattice Energy

​the energy required to separate the ions of an ionic compound is called lattice energy.

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​Lattice energy is greater when the charge on the ions is greater.

​Lattice energy is greater when the distance between the two ions is smaller.

​Metallic Bonds

​Electron Sea Model proposes that all the metal atoms in a metallic solid contribute their valence electrons to form a "sea" of electrons that surround the metal cations in the lattice.

​Delocalized Electrons

​The electrons are not held by any specific atom and they are free to move.

​A metallic bond is the attraction of a metallic cation for delocalized electrons.

​Properties of Metals

​In general metals have high melting and boiling points (except Hg as a liquid at room temperature).

Malleability, Ductility, Durability

Thermal & Electrical conductivity

Hardness & Strength (More delocalized electrons means greater strength)

​Alloys

​A homogeneous mixture of metals

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​Alloys are made to vary properties of metals (increase strength)

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​Substitutional Alloys - two metals of similar size are mixed.

​Interstitial Alloys - Large and small metals are mixed.