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54 Cards in this Set
- Front
- Back
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What is ionic substitution?
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ionic substitution is the replacement of one chemical element for another within the atomic structure of an ionically-bonded mineral
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What 2 factors control the ability of one ion to substitute for another?
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1. the size of the atoms
2. the magnitude of ionic charge (+3 -2 +1 +6...) |
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What is an angstrom?
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an angstrom is the unit used to measure distances within an atom.
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What is one angstrom equal to?
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1 angstrom = 1/10,000,000 mm
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why is the ionic radius more important in substitution than an atomic radius?
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because only ions substitute for eachother and therefore it is the radius of the ion that matters. Electrically neutral atoms cannot substitute for ions.
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in terms of size alone, what permits unlimited substitution between two ions?
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UNLIMITED substitution can occur between two ions provided their ionic radii doesn't differ by more than 15%
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What permits LIMITED substitution between two ions?
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LIMITED substitution occurs when the size difference between the two ions is between 15 and 35%. NO IONIC SUBSTITUTION occurs when ionic radii differs by more than 35%
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For chemical elements that exist with more than one charge (i.e. Mn+2, Mn+3, Mn+4), does the ionic radius INCREASE or DECREASE as the atomic number increases? Why?
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The ionic radius DECREASES because the same number of protons exert a stronger attraction for a diminishing number of electrons
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For different ions with an identical electron configuration (Na, Mg, All, Si, P), does the ionoic radius INCREASE or DECREASE as the charges increase? Why?
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The ionic radius DECREASES because an increasing number of protons exert a stronger attraction for the same number of electrons
Al+3 (with 2 shells) has a smaller ionic radius than Mg+3 |
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For chemical elements in the same vertical group of the periodic table (Li, Na, K) does their ionic radius INCREASE or DECREASE as the atomic number increases? Why?
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The ionic radius INCREASES because the number of electron orbital shells increase.
K+1 (3 shells) has a larger ionic radius than Na+1 (2 shells) or Li+1(1 shell) |
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What restriction is placed on the difference in charge in ionic substitution?
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Ionic stubstitution cannot occur when the difference in charge of the ions is greater than 1. This is due to the difficulty in rebalancing the charge requirements by other substitutions.
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What 2 pairs of ions commonly substitute for each other that have EQUAL charges
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Iron and Magnesium (Fe+2 Mg+2)
Fluorine and Hydroxide (F-1 OH-1) |
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What 2 pairs of ions commonly substitute for eachother that have unequal charges
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Sodium and Calcium (Na+1 Ca+2)
Silicon and Aluminum (Si+4 Al+3) |
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How are substitutions between ions of UNEQUAL charge compensated for?
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when a substitution occurs between two ions of unequal charge, another substitution of unequal charge must occur between a different pair of ions so that the electrical neutrality of atomic structure is maintained. This is known as COUPLED SUBSTITUTION
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what is coupled substitution?
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coupled substitution: ionic substituition that occurs between 2 pairs of different chemical elements within the same atomic structure at the same time. This happens when one substitution offsets the electrical charge (+1 substitutes for +2) and so another substitution occurs that re-establishes the neutrality (a +4 for a +3)
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What is a SOLID SOLUTION?
Name 2 examples |
A solid solution is the complete mixing of 2 chemically different minerals to form a single completely homogeneous mineral.
2 examples: Olivine -solid solution series between forsterite and fayalite Plagioclase -solid solution series of anorthite and albite |
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What is polymorphism?
Name examples |
Polymorphism is the occurrence of 2 or more minerals of identical chemical composition but each with a different atomic structure
Examples: -diamond and graphite -marcasite and pyrite -calcite and aragonite -andelusite, kyanite and sillimanite |
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what value are polymorphs to the science of geology?
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a polymorph indicates the temperature and pressure during the time it was formed
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what is isomorphism?
name some examples |
isomorphism is the occurrence of 2 or more minerals with an identical atomic structure but each with a different chemical composition.
Examples: native elements like copper, silver and gold |
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What is psuedomorphism?
examples |
psuedomorphism is the occurrence of a substance with the chemical composition of one mineral but the atomic structure of another.
Examples: limonite after pyrite quartz after asbestoes talc after actinolite halite after gypsum |
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What 5 conditions must be met for a substance to qualify as a mineral?
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1. solid
2. naturally occurring 3. completely inorganic 4. homogenous 5.possess a patterned atomic structure |
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what is a mineraloid?
example |
a mineraloid satisfies all the requirements of a mineral except that it does NOT possess a patterned atomic structure, thus, a mineraloid is said to be amorphous (without form).
Ex: Limonite and bauxite are examples of a mineraloid. |
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What is a mineral aggregate?
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a mineral aggregate refers to a characteristic shapre or form that a mineral often BUT NOT ALWAYS displays. Aggregate type usually facillitates identification.
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What is meant by the luster of a mineral?
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Luster refers to the way the surface of a mineral reflects light
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What are all minerals made of?
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atoms
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What 3 subatomic particles make up a single atom?
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1. protons
2. neutrons 3. electrons |
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what is the specific electrical charge for each of the subatomic particles?
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the proton has a positive charge, electron has a negative charge, a neutron has no charge
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what is the difference in mass between each of the subatomic particles?
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a neutron is just a wee-bit more massive than a proton. A single electron has 1/1837 the mass of a single proton. Said another way, it takes 1837 electrons to equal the mass of 1 proton
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what causes atoms to be attracted to one another?
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the positive charge of protons in the nucleus of an atom are attracted to the negative charge of the electrons of neighboring atoms
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what is a valence electron?
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a valence electron is the one that orbits in the outermost orbital shell of an atom that is NOT FILLED TO CAPACITY
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what single factor determines the ability of one atom to bond with another atom?
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the number of valence electrons
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some atoms are electron donors. What does this mean?
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an electron donor is an atom that transfers its valence electrons to another atom
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some atoms are electron acceptors. What does that mean?
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an electron acceptor is an atom that receives valence elecrons from a donor
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what is an ion?
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an ion is an atom with an unequal number of protons and electrons. Ions possess a charge of either positive or negative
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what is the difference between a cation and an anion?
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a cation is an ion with a positive charge. an anion is an ion with a negative charge
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in terms of electrons, what is the difference between metals and non-metals?
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Metals donate their valence electrons and become cations.
Nonmetals accept valence electrons and become anions. |
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How does ionic bonding occur?
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Ionic bonding occurs when one atom donates its valence electrons to an atom that accepts them. The donating atom becomes a cation and the accepting atom becomes anion. The attraction between their opposite charges bonds the two atoms together.
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how does covalent bonding occur?
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covalent bonding occurs when two or more atoms share valence electrons with eachother. The attraction between the protons of one atom and the electrons of the other atom bonds the two atoms together.
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how does metallic bonding occur?
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metallic bonding occurs when atoms of metals with large atomic numbers lose their valence electrons and become cations. The lost electrons are then "free" to form a "sea of electrons" that surrounds the cations. The attraction between the protons of the cations and the negative charge in the "sea of electrons" bonds the cations together. There are no anions in metallic bonding.
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In terms of metals and non-metals of what does an ionic bond usually consist?
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an ionic bond usually occurs between metal and non-metal
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in terms of metals and nonmetals, what does a covalent bond usually consist?
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covalent bonds usually occur between non-metals
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in terms of metals and nonmetals, what does a metallic bond usually consist?
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a metallic bond is always metals
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what is the Van der Wals bond?
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The Van der Waals bond is the attraction between the positive side of one polarized atom and the negative side of another polarized atom
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Which specific bond type(s) give a mineral: a high melting temp
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covalent
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Which specific bond type(s) give a mineral: superior hardness
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covalent
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Which specific bond type(s) give a mineral: high electrical conductivity
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metallic
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Which specific bond type(s) give a mineral: a greasy or smudgy feel
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van der waals
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Which specific bond type(s) give a mineral: solubility in water
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ionic
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Which specific bond type(s) give a mineral: insolubility in water
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covalent and metallic
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Which specific bond type(s) give a mineral: low thermal conductivity
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covalent and ionic
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why ar eminerals with metallic bonds good head conductors?
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head is generated by the accelerated movment and collision of electrons. In minerals with metallic bonds, the "sea of electrons" are free to move between atoms from one side of the mineral to the other, thus conducting heat throughout the structure
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Why are minerals with ionic and covalent bonds bad heat conducting?
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in minerals with ionic or covalent bonds, electrons have eitherbeen transferred from one atom to another OR the are shared b adjacent atoms. In either case, all elecrons continue to orbit the nucleus of an atom, thus NOT being free to collide with other electrons or move from one side of the mineral to the other. As a result, heat is not conducted within the atomic structure.
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In which bond type do the orbital shells of the valence electrons actually overlap?
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the covalent bond
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in what 2 very significant ways is the VAN DER WAALS bond different from the 3 other main types of bonds?
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the Van der Waals is different from the others in that:
1. it does not involve any transfer (ionic), sharing (covalent) or loss without acceptance (metallic) of an atoms valence electrons 2. it does not constitute the sole bonding type of any single mineral |
