Date post: | 13-Jan-2016 |
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Objectives
• Explain how the chemical bonds of a crystal determine the substance’s properties.
• Describe and give examples of mineral crystals.
Mineral Properties
• A mineral is a naturally occurring solid.
• It has a crystal structure and a definite chemical composition.
• A few are elements.
• Most are compounds.
Mineral Properties -- cont’d
• Properties include:• Color• Shininess• Density• Crystal shape• Hardness• Magnetism
Mineral Properties -- cont’d
• Minerals break into regular shapes.• Splits easily easily along fat surfaces and at
sharp angles.• Crystals also grow in characteristic shapes.• All properties depend on its chemical
composition.• Each mineral is different because each has a
different chemical composition.
Bonding in Mineral Crystals
• The arrangement of particles in a mineral and the kind of bonds holding them together determine properties such as crystal shape, hardness, and the way the crystal breaks apart.
An Ionic Crystal
• Example is Halite.• Made of sodium
chloride.• Soft.• Easily dissolved.• Even breaks
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Covalent Crystal
• Example is Quartz.• Covalent bonds are
strong.• Won’t dissolve in
water.• Hard• No defined lines of
weakness.
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