H. Chemistry Exam Review

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honors chemistry

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

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