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62 terms

H. Chemistry Exam Review

honors chemistry
STUDY
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Partial Pressure
the pressure that a particular gas would exert if it were alone in a container
5 Postulates of Kinetic Molecular Theory
Gases consist of atoms or molecules. These particles are so small when compared to the distance between them that their volume is assumed to be zero. The particles in a gas are in constant random motion making perfectly elastic collisions with each other and with the container. Particles are assumed not to attract or repel each other. The average kinetic energy of the particles is directly proportional to Kelvin temperature.
STP
standard temperature and pressure
The difference between Effusion and Diffusion
diffusion is the mixing of gases; effusion is the passage of a gas through a tiny orifice into an evacuated chamber.
When does a gas behave a close to ideal as possible?
At high pressure and low temperature
The photoelectric effect
refers to the phenomenon in which electrons are emitted from the surface of a metal when light strikes it.
The Heinsenberg Uncertainty Principle
it is not possible to simultaneously know information about the location and momentum of an electron
Orbital
a specific wave function
S orbitals
spherical; increase in energy and size based on "n"
P orbitals
no 1p orbital; not spherical; increase in size with increasing "n"; 2 lobes with nucleus at center
D orbitals
no 1d or 2d orbitals
F orbitals
no 1f, 2f, or 3f orbitals; most complex shape; occur in (first) n=4 level
Pauli Exclusion Principle
in a given atom, no 2 electrons (in the same orbital) can have the same set of 4 quantum numbers (n, l, ml, ms)
Aufbau Principle
as protons are added one by one to the nucleus to build up elements, electrons are similarly added to these hydrogen-like orbitals
Hund's Rule
the lowest energy configuration for an atom is the one having the maximum number of unpaired electrons allowed by the Pauli Principle in a particular set of degenerate orbitals
Periodic Trends
a characteristic of atom based on placement of periodic table
Atomic Radius (trend)
distance from center of nucleus to outermost electron; increases going down and to the left
Nuclear shielding
the more electrons, the tighter they are
Ionazation energy (trends)
energy required to remove an electron from an atom in its gas phase; increases towards right and up
Electron Affinity (trends)
tendency of an atom to gain an electron; increases towards right and up
Electronegativity (trends)
pull by an atom in a covalent bond on the shared electron(s); increases right and up; pull towards stronger atom
Formal charge
the difference between the number of valence electrons on the free atom and the number of valence electrons assigned to the atom in the molecule
Octet rule
all atoms will share as many electrons as necessary to have 8
Chemical Bond
the energy that holds two atoms together in a compound
Bond Energy
the energy required to break a bond
Ionic Bonding
the electrostatic attraction between oppositely charged ions
Covalent bonding
a type of bonding in which electrons are shared by atoms
Difference between covalent and ionic bonding
Ionic bonding is between metals and nonmetals; stronger; electrons are totally given up; they conduct electricity; Covalent bonding is between 2 nonmetals and electrons are shared.
Difference between single, double, and triple bonds
bond energy, length, and number of electrons involved
Resonance
invoked when more than one valid Lewis structure can be written for a particular molecule
VSEPR
valence shell electron pair repulsion
When is hybridization necessary?
When orbitals overlap
Sigma bond
bond directly between two atoms
Pi bond
bond above or below
Gas
no definite shape or volume
Liquid
no definite shape but definite volume
Solide
definite shape and volume
Why does ice float?
ice floats because it is less dense than water
Difference between intra and intermolecular forces
intramolecular forces are within one molecule, ionic and covalent bonds, stronger; intermolecular forces are between 2 molecules
Heating curve
x-time; y-temperature
Molar heat of fusion
enthalpy change that occurs at the melting point (kJ/mol)
Molar heat of vaporization
enthalpy change that occurs at the boiling point
London dispersion forces
van-der Waals forces; weakest; attractive forces that arise between the positive and negative sides of an instantaneous dipole; all substances contain these
KMT
explains the forces between molecules and the energy that they possess
Dipole-Dipole forces
they occur in molecules that are permanently polar versus momentarily polar. In this type of intermolecular interaction, a polar molecule such as water or H2O attracts the positive end of another polar molecule with its negative end of its dipole. The attraction between these two molecules is the dipole-dipole force.
Ion-Dipole forces
an attractive force that results from the electrostatic attraction between an ion and a neutral molecule that has a dipole. A positive ion (cation) attracts the partially negative end of a neutral polar molecule. A negative ion (anion) attracts the partially positive end of a neutral polar molecule. Ion-dipole attractions become stronger as either the charge on the ion increases, or as the magnitude of the dipole of the polar molecule increases.
Dipole-Induced Dipole Interactions
When charged particles near neutral atom, electrons shift accordingly; attraction occurs between oppositely charged ends of a true dipole molecule and induced dipole; don't last long
Hydrogen Bonding forces (Special Dipole-Dipole)
strongest; between hydrogen of one dipole and N, O or F dipole moment; N, O, or F has to be bound to another H
Momentary Assymetrical Electron Distribution
any given moment the electrons are distributed assymetrically; holds solids together
When are LD forces stronger than others LD?
larger and heavier atoms/molecules have stronger LD forces than smaller
vapor pressure
the pressure of the gas above a liquid in a closed container
volatile
higher vapor pressure; the weaker/lower the intermolecular forces, the more volatile
The 2 main types of solids
Amorphous (irregular arrangement, such as glass) and Crystalline (normal arrangement, such as diamonds)
The 3 Crystalline solids
Ionic solids (made of ions), molecular solids (made of covalent molecules), and Atomic solids (made of atoms)
Alloy
a mixture of metals; substitutional alloy- when you have the main element and substitute some of its atoms with littler ones (instruments; brass); interstitial alloy- take major atoms and fit little other atoms of a different element in between spaces (steel)
Phase Diagram
x- temperature; y-pressure
Triple point
the point at which all three phases occur at the same time
Critical point
the point at which it must be a gas
Aqueous solution
a solution in which water is the dissolving medium or solvent
"Like dissolves Like"
polar compounds will dissolve polar compounds and nonpolar compounds will dissolve nonpolar compounds
Dilute
Made thinner or weaker by having had water or another solvent added to it
Concentrated
unable to dissolved anymore solute