Chemistry Exam 2

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Formal Charge formula

Fc= # val e⁻ - ( # nonbonding e⁻ + 1/2(#bonding e))

Iron (iii) bromide

FeBr₃

Hydrogen carbonate or bicarbonate

HCO₃⁻

chloric acid

HClO₃

Hydrogen phosphate

HPO₄²⁻

Hydrogen sulfite or bisulfite

HSO₃⁻

Dihydrogen phosphate

H₂PO₄⁻

pm to nm

pm ∙ 1nm/1000pm

sp3d2 hybrid orbitals

six equivalent hybrid orbitals pointing towards the vertices of an octahedron that form by mixing one s orbital, three p orbitals, and two d orbitals from the same shell.

NaCH₃COO

sodium acetate

Energy levels of orbitals

sp3<sp2<sp

antibonding orbital

term in MO theory describing regions of electron density in a molecule that destabilize the molecule because they do not increase the electron density between nuclear centers.

bonding orbital

term in MO theory describing regions of increased electron density between nuclear centers that serve to hold atoms together in molecules.

valence

the capacity of the atoms of an element to form chemical bonds

sphere of hydration

the cluster of water molecules surrounding an ion in an aqueous solution.

solvent

the component of a solution that is present in the largest number of moles.

bond length

the distance between the nuclear centers of two atoms joined together in a bond

What is Eel inversely proportional to?

the distance between the two particles

electrostatic potential energy (Eel) (coulombic attraction)

the energy a charged particle has because of its position relative to another charged particle

lattice energy (U)

the energy released when 1 mole of an ionic compound forms from its free ions in the gas phase

solubility

the maximum quantity of a substance that can dissolve in a given volume of solution.

viscosity

the measure of the resistance to flow of a fluid.

Phosphate

PO₄³⁻

KNO₂

Potassium nitrite

Thiocyanate

SCN⁻

Sulfite

SO₃²⁻

Sulfate

SO₄²⁻

Bonding in metals is best described as ______ a. a transfer of electrons between many atoms. b. a network of covalent bonds. c. a sea of pooled electrons. d. highly directional and localized. e. completely electrostatic

c a sea of pooled electrons.

organic compounds

compounds that contain carbon, hydrogen, and sometimes toher elements including oxygen, nitrogen, sulfur, and a halogen.

chiral

describes a molecule that is not superimposable on its mirror image.

diamagnetic

describes a substance with no unpaired electrons that is weakly repelled by a magnetic field.

paramagnetic

describes a substance with unpaired electrons that is attracted to a magnetic field.

Coulomb's law states that the interaction energy between ions depends ______ a. only on the ionic charges. b. only on the distance between the ions. c. directly on both the ionic charges and the distance between the ions. d. on the temperature. e. directly on the ionic charges and inversely on the distance between the ions.

e. directly on the ionic charges and inversely on the distance between the ions.

sp3d orbitals

five equivalent hybrid orbitals with lobes pointing toward the vertices of a trigonal bipyramid that form by mixing one s orbital, three p orbitals, and one d orbital from the same shell.

molecular orbital diagram

in MO theory, an energy-level diagram showing the relative energies and electron occupancy of the molecular orbitals for a molecule.

pi molecular orbital

in MO theory, an orbital formed by the mixing of atomic orbitals oriented above and below, or in front of and behind, the bonding axis; electrons in pi orbitals form pi bonds.

sigma molecular orbital

in MO theory, the orbital that results in the highest electron density between the two bonded atoms.

hybrid atomic orbital

in valence bond theory, one of a set of equivalent orbitals about an atom created when specific atomic orbitals are mixed.

hybridization

in valence bond theory, the mixing of atomic orbitals to generate new sets of orbitals that then are available to form covalent bonds with other atoms.

stereoisomerism

isomerism created by differences in the orientations of the bonds between atoms in molecules.

miscible

liquids that are mutually soluble in any proportion

molecular recognition

the process by which molecules interact with other molecules to produce a biological effect.

What is Eel directly proportional to?

the product of the charges of the particles

polarizability

the relative ease with which the electron cloud in a molecule, ion, or atom can be distorted, inducing a temporary dipole

temporary dipole

the separation of charge produced in an atom or molecule by a momentary uneven distribution of electrons; also called induced dipole.

hydrogen bond

the strongest dipole-dipole interaction, which occurs between a hydrogen atom bonded to a N, O, or F atom and another N, O, or F atom.

sp2 hybrid orbitals

tthree hybrid orbitals in a trigonal planar orientation formed by mixing one s and two p orbitals.

sp hybrid orbitals

two hybrid orbitals on opposite sides of the hybridized atom formed by mixing one s and one p orbital.

Calculate the electrostatic potential energy in J of the interaction of one magnesium ion (86 pm radius) and one bromide ion (182 pm radius) in magnesium bromide.

-1.7x10⁻¹⁸J

Estimate the enthalpy of reaction, H⁰, for 2H₂(g) + O₂(g)→2H₂O(g) using bond energies. Bond ------------ 0=0 O-H H-H Energy(kj/mole) 498 463 436

-482 kJ/mol

Rules of MO theory

1. The number of molecular orbitals equals the number of atomic orbitals used to create them. 2. Atomic orbitals with similar energy and orientation mix more effectively than do those that have different energies and orientations. 3. Better mixing leads to a larger energy difference between bonding and antibonding orbitals and thus greater stabilization of the bonding MOs. 4. A molecular orbital can accomodate a maximum of two electsons; two electrons in the same MO have opposite spins. 5. Electrons in ground-state molecules occupy the lowest energy molecular orbitals available, following the aufbau principle and Hund's rule.

Cr₂S₃

Chromium (iii) sulfide

Which of the following will have the largest ( most negative) lattice energy? a. NaF b. NaCl c. NaBr d. NaI e. CsCl

A. NaF

Hypochlorite

ClO⁻

Chlorite

ClO₂⁻

Chlorate

ClO₃⁻

Which of the following will require the greatest energy input to separate the ions? a. MgI₂ b. MgF₂ c. MgCl₂ d MgBr₂ e NaCl

B MgF₂

Acetate

CH₃COO⁻

Cyanide

CN⁻

Carbonate

CO₃²⁻

Ca₃(PO₄)₂

Calicum Phosphate

Perchlorate

ClO₄⁻

Chromate

CrO₄²⁻

Dichromate

Cr₂O₇²⁻

Which of the following statements regarding ionic compound is zero? a. The net charge of an ionic compound is zero. b. Oppositely charged ions collect together in part because isolated ions are not stable. c. The energy associated with an ionic bond is a form of electrostatic potential energy d. Ions are held together by shared pairs of electrons e. Oppositely charged ions arrange themselves to minimize repulsions an maximize attractions.

D. Ions are held together by shared pairs of electrons

Eel=

Eel=2.31x10⁻¹⁹J ∙nm (Q¹-Q₂)/d

Permanganate

MnO₄⁻

Draw the Lewis structure for the ion, OCN-. Show all relevant resonance structures and circle the best one based on formal charges.

N=C-O O=C=N O(triple bond)- C-N ( N-C triple bond) the first one is the best

Ammonium

NH₄⁺

Nitrite

NO₂⁻

Nitrate

NO₃⁻

dinitrogen pentoxide

N₂O₅

Azide

N₃⁻

Hydroxide

OH⁻

Disulfide

S₂²⁻

isomer

one of a group of compounds having the same chemical formula but different molecular structures

enantiomer

one of a pair of optical isomers of a compound.

Draw the Lewis structure for MgF₂

[Mg]²⁺[F]¹⁻[F]¹⁻ and draw full electrons pairs for the two fluorine

covalent bond

a bond created by two atoms sharing one or more pairs of electrons

molecular orbital (MO) theory

a bonding theory based on the mixing of atomic orbitals of similar shapes and energies to form molecular orbitals that belong to the molecule as a whole.molecular orbital a region of characteristic shape and energy where electrons in a molecule are located.

pi bond

a covalent bond in which electron density is greatest above and below the bonding axis.

sigma bond

a covalent bond in which the highest electron density lies between the two atoms along the bond axis.

aromatic compound

a cyclic, planar compound with delocalized pi electrons above and below the plane of the molecule.

carbonyl group

a functional group that consists of a carbon atom with a double bond to an oxygen atom.

hydroxyl group

a functional group that consists of an oxygen atom with a single bond to a hydrogen atom.

alkane

a hydrocarbon in which each carbon atom is bonded to four other atoms.

dipole moment

a measure of the degree to which a molecule aligns itself in an applied electrical field; a quantitative expression of the polarity of a molecule.

valence bond theory

a quantum mechanics-based theory of bonding that assumes covalent bonds form when half-filled orbitals on different atoms overlap or occupy the same region in space.

racemic mixture

a sample containing equal amounts of both enantiomers of a compound.

sp3 hybridization

a set of four hybrid orbitals with a tetrahedral orientation produced by mixing one s and three p atomic orbitals.

overlap

a term in valence bond theory describing bonds arising from two orbitals on different atoms that occupy the same region of space.

dipole-dipole interactions

an attraction between regions of polar molecules that have partial charges of opposite sign

ion-dipole interaction

an attractive force between an ion and a molecule that has a permanent dipole.

London dispersion force

an intermolecular force between nonpolar molecules caused by the presence of temporary dipoles in the molecules.

crystal lattice

an ordered three-dimensional array of particles (atoms, ions, or molecules)

alcohol

an organic compound whose molecular structure includes a hydroxyl group bonded to a carbon atom that is not bonded to any other functional group(s).

hydrocarbon

an organic compound whose molecules contain only carbon and hydrogen atoms.

solute

any component in a solution other than the solvent. A solution may contain one or more solutes.

Which of the following is the shortest bond? The number in parentheses is the bond energy. a. c-c (248 kj/mol) b. C-F (453 kj/mol) cC-H (411 kj/mol)

b. C-F (453 kj/mol)

constitutional isomer

one of a set of compounds with the same molecular formula but different connections between the atoms in their molecules; also called structural isomers.


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