General Chemistry 163A Study Guide

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General Chemistry 163A Study Guide

Chapters 1 and 2

States of matter: solids, liquids, and gases

Classification of matter: matter, pure substances, compound vs. element, mixtures: homogeneous (solutions) vs. heterogeneous mixtures

Methods of separating mixtures: distillation, chromatography, crystallization, filtration; solubility differences

Density = mass/volume; intensive property (vs. extensive properties)

Metric system and measurement; uncertainty and significant figures; unit multipliers

Precision vs. accuracy

Atomic theory-John Dalton; law of constant composition; law of multiple proportions; law of conservation of energy

J.J. Thomson discovers the electron in 1897 (cathode rays); charge/mass ratio for electron found as 1.76 x 10

8

C/g

Robert Millikan’s oil drop experiment yields the charge on the electron = 1.6 x

10

-19

C; sets mass of electron at 9.1 x 10

-31

kg

Ernest Rutherford discovers the nucleus in 1911; alpha scattering experiment; nucleus is 10,000 times smaller than atom, contains 99.99% of atoms mass and all the positive charge

Atomic number; mass number; isotopes; average atomic mass; ions; oxidation number

Periodic table; periods; columns; periodicity-similar chemical properties yields families of elements; metals, nonmetals, metalloids

Empirical formulas; molecular formulas

Nomenclature; naming systems for compounds and ions

Chapters 3 and 4

Writing balanced chemical equations; subscripts vs. coefficients; conserving atoms during chemical changes is based on work of Antoine Lavoisier (law of conservation of mass)

Identifying types of chemical reactions: combination vs decomposition reactions; combustion reactions

Formula weights; molecular weights; molar masses; atomic mass units vs. grams

(1 gram = 6.02 x 10

23

Stoichiometry: grams

amu)

moles

 molecules

atoms

Determining empirical formulas and molecular formulas

Limiting reactant, theoretical yield, actual yield, percent yield problems

Solutions: molarity = moles per liter of solution; electrolytes, solubility, solutes, solvents, “like dissolves like” = polar solutes dissolve in polar solvents

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Exchange reactions; precipitates, spectator ions, molecular equation, ionic equation, net ionic equation

Acid = proton donor or substance dissolving in water to produce H

+1

ions; base = proton acceptor or substance dissolving in water to produce hydroxide ions, OH

-1

Arrhenius neutralization reactions: acid + base = salt + water; H

+1

+ OH

-1

= H

2

O

Oxidation-reduction reactions: oxidation = loss of electron(s); reduction = gain of electron(s); oxidizing agent; activity series; displacement (exchange) reaction:

(lab) Cu

(s)

+ 2Ag

+1

(aq)

= 2 Ag

(s)

+ Cu

+2

(aq)

; identifying oxidation numbers of monatomic ions and elements in a polyatomic ion

Chapters 6 and 7

E n

 13.6 eV n 2

E photon

 h  ; h = 4.15

 10 -15 eV  s = 6.63

 10 -34 J  s

E photon

 = h

1240 eV  nm

 mv

Electromagnetic waves have wavelength,

, frequency,

, and c =



= 3 x 10 8 m/s

The electronic structure of atoms has been worked out over time by putting our ideas to the test: Max Planck (quantum theory); Niels Bohr (solar system model);

Louis deBroglie (matter waves); Werner Heisenberg (uncertainty principle);

Erwin Schrodinger (wave equation) and Quantum Mechanics => quantum numbers and orbitals, energy states, valence electrons

Quantum of energy; photons; E = h

; line spectra and excitation vs. emission; hydrogen: E n

= -13.6 eV/n

2

, n = principal quantum number

Electrons have dualistic nature: sometimes behaving as particles and sometimes behaving as waves; deBroglie and

= h/mv; matter waves discovered in 1927 at

Bell telephone labs (Davisson and Germer)

Uncertainty principle: there is a limit as to how precise we can know the position and momentum of an electron in an atom: (

 x) x (

 mv) ≥ h/4π

 Schrodinger’s wave equation can be solved to yield position probabilities and energies of electrons in atoms

Quantum numbers: n, l

, and m l

identify distinct orbitals in atoms; hydrogen: for each level, n, there are n

2

orbitals; s, p, d, and f orbitals come in sets of 1, 3, 5, and

7

 n = 1, 2, 3, …; l

= 0, 1, …, n – 1; m l

= -

l to 0 to

– l

Pauli exclusion principle: no two electrons in an atom can have the same set of quantum numbers; magnetic spin quantum number, m s

, distinguishes between the two electrons that can coexist in an orbital

Auf bau principle: electrons are added to orbitals of increasing energy, in general, filling each to capacity before beginning the next; Hund’s rule: when electrons are

added to degenerate orbitals, they are added such that the electrons remain as unpaired as possible

Electron configurations: 1s

2

2s

2

2p

6 …etc; valence orbitals are generally the outer s and p orbitals; successive ionization energies provide evidence for energy levels and shells

Effective nuclear charge: the amount of positive charge in the nucleus that a particular electron in an atom can actually feel; screening effect of core electrons;

Z eff

= Z-S

Trends in atomic size, ionization energy, and electron affinity; metallic character trend

 Noble gases are the key to understanding the elements’ characteristics; unreactive gases have completed energy levels of electrons and a stable octet of valence electrons

Alkali metals, alkaline earth metals, halogens, noble gases: representative elements to be familiar with

Distinguishing metals and nonmetals: properties

Chapters 8 and 9

Chemical bonding: ionic, covalent, and metallic bonding

Ions of the representative elements have noble gas electron configurations; metals form positive ions (low ionization energies and low effective nuclear charge associated with valence electrons); nonmetals form negative ions (high ionization energies, more negative electron affinities, and higher effective nuclear charge associated with valence electrons)

Lattice energy and Born-Haber cycle describes the energetics associated with the formation of one mole of an ionic compound from its elements

Covalent bonding involves the sharing of electrons; half-filled orbitals overlap;

Lewis symbols and structures represent the bonding of nonmetals in molecular compounds

Octet rule: atoms tend to gain, lose, or share electrons in acquiring eight valence electrons

Multiple bonding results in stronger bonding and shorter bond distances

Bond polarity can be determine by electronegativity differences: ionic vs. polar covalent vs. nonpolar covalent bonding; electronegativity trends; bond dipoles

VSEPR theory: valence shell electron pair repulsion theory; electron domains position themselves so as to minimize repulsions

Electron domain geometries; linear, trigonal planar, tetrahedral, trigonal bipyramidal; and octahedral shapes

Molecular shapes are determined by the numbers of lone pairs (LP) and bond pairs (BP) of electrons: linear; trigonal planar and bent; tetrahedral and trigonal pyramidal and bent; trigonal bipyramidal and seesaw and T-shaped and linear; octahedral and square pyramidal and square planar

Valence bond theory: atoms bond covalently via orbital overlaps; sigma (

) bonds involve end-to-end overlapping of orbitals; pi (π) bonds form when unhybridized

p orbitals overlap sideways; sigma bonds have more overlap and are stronger than pi bonds

Hybridization of atomic orbitals: in order to explain the shapes of molecules, we have to hybridize atomic orbitals; s + p = two sp hybrids, directed at 180° with respect to each other; s + p + p = three sp

2

hybrids, directed at 120° with respect to each other; s + p + p + p = four sp

3

hybrids, directed at 109.5° with respect to each other; s + p + p + p + d = five sp 3 d hybrids, directed according to trigonal bipyramidal geometry; s + p + p + p + d + d = six sp

3 d

2

hybrids, directed according to octahedral geometry

 formal charge is the charge associated with an atom in a molecule = # valence electrons - # electrons assigned to atom in the molecule; formal charge can lead to a more stable Lewis structure when several alternatives are found

Resonance structures: equivalent Lewis structures that include multiple bonds; bond strengths and bond distances are averaged in resonance scenarios; delocalized electrons are shared between many electrons in resonance structures

Chapter 10

Atmospheric pressure: gas pressure = force/area; barometer, barometric pressure determined by the height of a column of mercury supported by the weight of the atmosphere

Manometers measure pressures of laboratory samples of gases; distinguish between open-end and closed-end manometers

Kinetic-molecular theory of gases: behavior of gases: gas laws; ideal gas is a hypothetical gas in which molecules take up no space and exert no electrical forces on each other; ideal gas law: PV = nRT

The kelvin temperature scale is the international metric unit of temperature; absolute zero of temperature = 0 K = -273 °C; K = °C + 273; at absolute zero, molecules have zero kinetic energy

 Boyle’s law: P ~ 1/V; P

1

V

1

= P

2

V

2

 Charles’ law: V ~ T; V

1

/T

1

= V

2

/T

2

Gay-Lussac’s law: P ~ T; P

1

/T

1

= P

2

/T

2

 Avogadro’s law: V ~ n; V

 Dalton’s law: P ~ n; P

1

1

/n

1

= V

2

/n

2

/n

1

= P

2

/n

2

; P total

= sum of partial pressures; P

1

=

1

P total where

1

is the mole fraction of component #1 in gas mixture

STP conditions = 273 K and 1.0 atm

Molar volume at STP = 22.4 L/mol (ideally)

Effusion vs. diffusion; effusion rates identify relative average molecular velocities of different gases; average molecular speeds are rms quantities ( r oot m ean s quare quantities); Graham’s law: the rms speed at a given temperature is inversely related to the square root of its molecular mass

The average translational kinetic energy of a collection of molecules is directly proportional to its Kelvin temperature

Tenets of the kinetic-molecular theory: molecules take up no space and exert no electrical forces on each other

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Real gases do take up space and their molecules exert attractive forces on each other. Johannes van der Waals developed an equation that predicts the nonideal behavior of gases:

(P  an 2

V 2

)(V  nb)  nRT

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