Exam 2 – Chemistry Test Answers – Flashcards

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question
What becomes a source of energy?
answer
Heat
question
Heat is the source of what?
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Energy
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What do we use to supply the energy we need?
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Chemical reactions.
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What do chemical reactions supply?
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Energy
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What is 1 cal?
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The amount of heat needed to raise the temperature of 1 g of water by 1C
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What is the amount of heat needed to raise the temperature of 1 g of water by 1C?
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1 cal
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Exothermic reactions...?
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Produce heat.
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Endothermic reactions...?
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Absorb heat energy from surroundings.
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What type of reaction absorbs heat energy from surroundings?
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Endothermic.
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What type of reaction produces heat?
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Exothermic.
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Carbohydrates provide...?
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4 kcal/g (4 Cal/g)
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Proteins provide...?
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4 kcal/g (4 Cal/g)
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Fats provide...?
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9 kcal/g (9 Cal/g)
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What is the rate of a reaction?
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The amount of products formed from reactants in a given period of time.
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What is the collision theory?
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Views the rate of a reaction as the result of particles colliding with certain frequency and minimum energy.
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Views the rate of a reaction as the result of particles colliding with certain frequency and minimum energy.
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Collision theory
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What must reactants do for a reaction to occur?
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Must collide, collide with proper orientation, and collide with sufficient energy.
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In an exothermic reaction who has the lower energy?
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Products are lower energy than the reactants.
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in an endothermic reaction who has the lower energy?
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In an endothermic reaction the reactants are lower energy than products.
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What are factors that affect reaction rates?
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Concentration, temperature, or presence of a catalyst.
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What effect does concentration have on reaction rates.
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More reactants = more collisions.
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What effect does temperature have on reaction rates?
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Higher speeds = more collisions.
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What does the coefficient in a reaction equation stand for?
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The number of molecultes (mols)
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Define equilibrium.
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The rate of the reactants to products is the same as the rate of products to reactants.
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What is the equilibrium constant?
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K = (products)/(reactants)
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K = (products)/(reactants)
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Equilibrium constant
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Preferred bonding pattern for H.
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H-
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Preferred bonding patterns for C
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l
-C-
l

>C=

=C=

-C(tri)C-
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Preferred bonding patterns for N
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..
-N -
l

..
- N -
l

:N(tri)
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Preferred bonding patterns for O
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..
-O -
''

..
O =
''
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Preferred bonding patterns for S
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..
- S-
''
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What is the VSEPR Theory?
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Electron charge clouds will arrange themselves to be as far away from each other as possible.
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What is electronegativity?
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The ability of an atom to attract bonding electrons of a covalent bond to itself.
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0 < 0.4 electronegativity
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Nonpolar
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Nonpolar bond in electronegativity
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0 < 0.4
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0.4 >
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Polar
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Polar bond in electronegativity
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0.4 >
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if the central atom has one or more pairs of nonbonding electrons, the molecule is...?
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Polar.
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If the central atom has no nonbonding pairs of electrons and all other atoms connected to the central atom are identical, the molecule is...?
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Nonpolar.
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If the central atom has no nonbonding pairs of electrons and at least one of the atoms connected to the central atom is different from the others, the molecule is...?
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Polar.
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Chromium ions
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Cr(2+ or 3+)
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Manganese ions
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Mn 2+
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Iron ions
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Fe 2+ or 3+
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Nickel ions
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Ni 2+
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Copper ions
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Cu 1+ or 2+
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Zinc ions
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Zn 2+
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A combination reaction is?
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Elements or simple compounds that react to make a more complicated compound.
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Elements or simple compounds that react to make a more complicated compound.
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Combination reaction
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Reactant is split into simpler compounds.
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Decomposition.
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A reaction with oxygen
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Combustion.
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Decomposition
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Reactant is split into simpler compounds.
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Combustion
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A reaction with oxygen.
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Single Replacement reaction
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One atom replaces another atom in a second compound (cation with cation).
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One atom replaces another atom in a second compound (cation with cation).
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Single replacement reaction
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What are the diatomic elements?
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H2, N2, F2, O2, I2, Cl2, Br2
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Double Replacement reaciton
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Positive ions switch places when two ionic compounds react.
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Positive ions switch places when two ionic compounds react.
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Double Replacement.
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What do saturated hydrocarbons contain?
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Only carbon-carbon single bonds.
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Simple organic compound names.
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Meth, eth, prop, but, pent, hex, hept, oct, non, dec.
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What are structural isomers?
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Compounds with same molecular formula, but different connectivity.
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Compounds with same molecular formula but different connectivity.
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Structural isomer.
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Stereoisomers are...?
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Compounds which differ from each other by their arrange of atoms in space.
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Compounds which differ from each other by their arrange of atoms in space.
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Stereoisomers.
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What are responsible for the spearmint and caraway seed flavor?
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A pair of stereoisomerrs called carvones that are taste buds can distinguish between them
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Difference between spearmint and caraway is...
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The stereoisomers are identical except for the arrangement of groups in space.
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Enantiomers are...
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Mirror images, but cannot be simply flipped because of 3-dimensionality.
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Mirror images, but cannot be simply flipped because of 3-dimensionality.
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Enantiomers.
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What is a chiral center?
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A tetrahedral carbon bonded to four different atoms or groups of atoms. Molecules with a chiral center form mirror images that are nonsuperimposable.
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What are intermolecular forces?
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The attractive forces between molecules.
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What are the attractive forces between molecules called?
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Intermolecular forces.
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What is weaker: intermolecular forces or covalent bonds?
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Intermolecular forces.
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What is the weakest of the forces?
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London (dispersion forces)
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When do london forces occur?
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Momentarily in all molecules when electrons become unevenly distributed over a molecule's surface.
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What is created in london forces?
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An induced dipole.
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Where are london forces significant in?
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Nonpolar molecules.
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When is a permanent dipole created?
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Only in polar molecules.
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What must be always done in when comparing intermolecular forces?
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Comparing molecules of similar molecular weight.
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When do dipole-dipole attractions occur?
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Between the dipoles of two polar molecules.
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What is hydrogen bonding?
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Interaction between two molecules, a donor and an acceptor.
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What is the hydrogen donor?
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A molecule with a hydrogen atom covalently bonded to an O, N or F
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What is the hydrogen acceptor?
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A molecule with a nonbonding pair of electrons on an O, N or F
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A molecule with a nonbonding pair of electrons on an O, N or F
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Hydrogen acceptor
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A molecule with a hydrogen atom covalently bonded to an O, N or F
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Hydrogen donor
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What is the strongest of the intermolecular forces?
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Hydrogen bonding.
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When is something soluble?
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Like dissolves like, soluble if the molecules can bond.
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What is the golden rule of solubility?
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Molecules that have similar polarity and participate in the same types of intermolecular forces will dissolve each other.
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Molecules that have similar polarity and participate in the same types of intermolecular forces will dissolve each other.
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What is the golden rule of solubility?
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Can there be cis-trans in single bonds?
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No.
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What can have cis-trans?
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Ring structures and double bonds.
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AB2
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Linear
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Linear
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AB2
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AB3
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Trigonal planar
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Ab2N
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Bent
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Bent
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Ab2N
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Trigonal planar
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AB3
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Ab4
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Tetrahedral
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Tetrahedral
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Ab4
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Ab3N
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Pyramidal
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Pyramidal
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Ab3N
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Ab2N2
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Bent
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