Download What Determines the Physical Properties of a Mineral?

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Introduction to the Building Blocks of Minerals
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What Determines the Physical Properties of a Mineral?
• Chemistry
• Internal structure
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Definitions:
¢ Mineral: any naturally-occurring, solid element or compound, with a crystalline
form and a defined chemistry
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Definitions:
¢ Mineral: any naturally-occurring, solid element or compound, with a crystalline
form and a defined chemistry
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Periodic Table of Elements
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The basic components of atoms
The nucleus is minuscule compared to the volume of the atom, but
contains most of the mass
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The basic components of atoms
The nucleus is made of protons and neutrons
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The basic components of atoms
wThe Electron mass = 1/1846 of a proton, charge = -1
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Atomic number
Every atom of the same element has the same number of protons in its nucleus – the
atomic number
Each element has a specific atomic number, which differs from the atomic number of
all other elements
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Atomic number
Every atom of the same element has the same number of protons in its nucleus – the
atomic number
Each element has a specific atomic number, which differs from the atomic number of
all other elements
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Atomic mass (weight)
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The number of neutrons in the nucleus can vary
without causing the atom’s identity to change;
the atomic mass (weight) may vary
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Two different models of an atom
Energy Levels of Electron Shells
Facts about atoms
outermost shell filled with electrons = STABLE CONFIGURATION
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Periodic table of elements
How are atoms bonded to form a mineral?
Ionic bonding
Ionic bonding
Ionic bonding
Ion – An electrically charged atom
nWhen an atom is missing electrons = cation; has a positive
charge (Na+)
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Ionic bonding
Ion – An electrically charged atom
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nWhen an atom is missing electrons = cation; has a positive
charge (Na+)
nWhen an atom has too many electrons = anion; has a negative
charge (Cl-)
Ionic bonding
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Halite (NaCl) – An example of ionic bonding
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Chemical compounds - Ionic bonding
The properties of a chemical compound are very different from the
properties of the elements comprising it.
Chlorine (Cl) gas = green, poisonous!
Sodium (Na) = soft, silvery metal
Cl- + Na+ = table salt!
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Covalent bonding
Atoms share electrons to achieve electrical neutrality
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Covalent compounds are generally stronger than ionic bonds
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Covalent bonding – sharing of valence electrons
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Ionic and covalent bonds
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wBoth ionic and covalent bonds typically occur in the
same compound (mineral)
wBonds are seldom 100% ionic or covalent in
character
Covalent bonding in diamond
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Metallic bonding (not chemical bonding)
Metallic bonding (not chemical bonding)
Valence electrons are free to
migrate among atoms
The migrating electron creates a “glue”
Weaker and less common than ionic or covalent bonds
Ex: Cu, Au, Al as a result have high electrical conductivity
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What does all this have to do with Earth materials?
Minerals as Crystalline Solids
The ions of a mineral are arranged in systematic, regular networks
whose geometric configurations are repeated.
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Crystal Lattice of Halite (NaCl)
What does all this have to do with minerals?
Oxygen is the most abundant element in the earth’s crust
Oxygen comprises 93% of the volume of an average rock
Silicon is the second most abundant element
Ex: Oxygen + Silicon = Quartz
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