Gen Chem Semester 1 Final

Actual yield

Amount of product obtained from an experimental determination

Angular momentum quantum number (l)

The quantum number defining the shape of an orbital. In multielectron atoms, it also partially defines the energy of the orbital.

Atomic mass unit

(amu, or just u) Mass unit determined by arbitrarily assigning the carbon-12 isotope a mass of 12 atomic mass units; 1 (am)u is approximately 1.6605 × 10-24 g

Atomic orbitals

The allowed wavefunctions for an atom. They determine the electron charge density or the probability of finding an electron in an atom. The several kinds of orbitals (s, p, d, f, . . . ) differ from one another in the shapes of the electron clouds they describe.

Atomic radius

(derived from metals, solid elements); ½ distance between centers of two adjacent atoms

Atomic symbols

One or two letters used to designate each of the elements

Atomic theory

A model of the structure of matter; postulate the existence of exceedingly small particles from which all matter is composed.

Atoms

Minute particles of which matter is composed; the smallest parts of an element that can enter into chemical reaction

Avogadro's Hypothesis (Law)

Equal volumes of any two gases at the same temperature and pressure contain the same number of molecules

Avogadro's number

(NA) Number of atoms in exactly 12 g of carbon-12; to four significant figures, 6.022 x 1023

Barometer

device for measuring the pressure of the atmosphere

Bond energy (enthalpy)

is the quantity of energy (usually expressed in kJ/mol) required to break one mole of chemical bonds in a gaseous species

Bond length (bond distance)

is the distance between the nuclei of atoms joined by a chemical bond.

Bond order

the number of electron pairs in a bond

Bonding pair

is a pair of electrons involved in bond formation.

Boyle's Law

the volume occupied by any given amount of gas at a fixed temperature varies inversely with its pressure

Building-up (Aufbau) principle (or process)

A method for predicting the ground state energy levels of the electrons in an atom

Carbon 12 relative atomic mass scale

Scale whereby relative atomic masses are assigned by dividing actual atomic masses by 1⁄12 of the actual mass of a carbon-12 atom

Charles's Law

the volume occupied by any given sample of gas at constant pressure is directly proportional to the absolute temperature

Chemical equation

Symbolic representation of a chemical reaction

Chemical properties

Characteristics of a pure substance that involve chemical change

Chemical reaction

Change in chemical identities of matter, that is, change of one or more substances into one or more different substances

Compounds

Kinds of mater composed of atoms of two or more elements

Compressibility

Ability to be squeezed into a smaller volume by the application of pressure

Concentration

Amount of solute dissolved in a given quantity of solvent or solution

Constructive interference

is the result of combining two waves that are of the same wavelength and in phase such that the intensity of the resultant ray is increased

Continuous spectrum

A spectrum containing light of all wavelengths

Covalent bonding

bonding from the sharing of electron pairs between atoms

Dalton's Law of Partial Pressures

the sum of the partial pressures of all the different gases in a mixture is equal to the total pressure of the mixture

Degenerate orbitals

have the same energy. In the hydrogen atom, all orbitals with the same n value (e.g., 3s, 3p, 3d) are degenerate. This is not true for multielectron atoms.

Delocalized bonding

is described in terms of regions of high electron probability or charge density that extends over three or more atoms.

Density

Mass per unit volume

Destructive interference

is the result of combining two waves that are of the same wavelength and out of phase such that the intensity of the resultant ray is reduced to zero, or destroyed

Diamagnetism

refers to the repulsion by a magnetic field of a species in which all electrons are paired.

Diffusion

process whereby a gas spreads out through another gas to occupy a space wherein the partial pressure is uniform

Effusion

escape of a gas through a small hole into a vacuum at the same velocity it had in the container

Elastic

term describing a collision in which no kinetic energy is lost

Electron affinity

is the energy associated with the gain of an electron by a gaseous atom

Electron configuration

the arrangement of electrons in the orbitals of an atom or molecule.

Electronegativity

is a measure of the electron attracting power of an atom; metals have low electronegativities; nonmetals, high.

Elements

Kinds of matter composed of atoms of only one chemically distinct type of an atom; pure substances that can be chemically decomposed into simpler substances

Empirical Formula

Combination of atomic symbols that gives the kinds of atoms and their simplest ratio in a substance

Energy levels

the specific energy values possessed by an electron in an atom

Enthalpy (H)

A state function that can be used to obtain the heat absorbed or evolved in a chemical reaction. It is equal to E + PV. The enthalpy change, ∆H, is equal to q at constant pressure; i.e., ∆H = qp.

First Law of Thermodynamics

A law stating that if a system does not exchange energy with its surroundings (i.e., it is closed (isolated)) the energy of system is constant. If a system does exchange energy with the surroundings, the sum of energy changes is constant. In symbols, ∆E = q + w

Formula unit

Simplest ratio of elements or ions in a compound

Formula weight

Sum of the atomic masses (weights) of all the atoms in a given formula

Frequency (n)

number of wavelengths of a wave that pass a fixed point in one unit of time

Graham's Law of Effusion

the rate of effusion of gas molecules from a particular hole is inversely proportional to the square root of the molecular weight of the gas at constant T and P

Group (of periodic table)

is a vertical column of elements in the periodic table; members of the group have similar properties.

Heat

The energy that flows into or out of a system because of a difference in temperature between the thermodynamic system and its surroundings.

Heat Capacity

The quantity of heat needed to raise the temperature of a substance. The specific heat capacity (cs) is the quantity of heat needed to raise 1 gram of a substance by 1 °C (or K).

Heisenberg Uncertainty Principle

The proposition advanced by Werner Heisenberg that the position and momentum of particles cannot be known exactly. Specifically, the product of uncertainly in position and the uncertainty in momentum (mass x speed) cannot be smaller than h/4π, or (∆x)(m∆v) ≥ h/4π

Heterogeneous mixture

Combination of two or more pure substances that are not uniform throughout

Homogenous mixture

Combination of two or more pure substances that are uniform throughout

Hund's Rule

The principle that states the for degenerate orbitals, the lowest energy is attained when the number of electrons with the same spin is maximized.

Ideal Gas Law

mathematical expression relating the volume (V), pressure (P), Kelvin temperature (T), and moles (n), of a gas with the molar gas constant, R (PV = nRT)

In

phase- said of two waves of the same wavelength that come together with their maxima and their minima at the same points

Ions

Electrically charged atoms or groups of atoms

Ionic bond

a bond in which an element of lower ionization energy (e.g., metals) transfers one or more e- to an element of higher electron affinity (usually non-metal) and the resulting cation(s) and anion(s) are held together by electrostatic forces of attraction

Ionic solids

are solids that consist of cations and anions held together by the electric attraction of opposite charges

Ionization energy (potential)

is the energy required to remove the most loosely held electron from gaseous atom.

Isoelectronic species

have the same number of electrons (usually in the same configuration): e.g., Na+, Ne, and F-

Isotopes

Atoms of the same element having different masses (by virtue of having

Kelvin scale

absolute temperature scale on which the units (kelvins, K) are given by K = °C + 273.15

Kinetic theory of gases

idea that gas pressure results from the continual bombardment of container walls by constantly moving molecules

Law

Generalization, based on experiment, about the behavior of nature

Law of Combining Volumes

Gases at the same temperature and pressure react with one another in volume ratio of small whole numbers

Law of Conservation of Mass

Mass remains constant during a chemical change or reaction

Line spectrum

A spectrum containing radiation of only specific wavelengths

Lone (nonbonding) pair

is a pair of electrons found the valence shell of an atom and not involved in bonding

Magnetic quantum number (ml)

A quantum number that describes the orientation of the orbital in space

Mass

The quantity of matter.

Mass percentages

Parts per hundred in terms of mass: Mass % of A = mass of A in the whole/mass of the whole x 100%

Maxwell's distribution of molecular speeds

range of speeds predicted for a given sample of gas molecules at constant temperature

Melting (freezing) point

temperature at which the liquid and solid are in dynamic equilibrium

Molar gas constant (R)

invariant (unchanging) factor relating the volume, temperature, and pressure of one mole of any gas; its numerical value varies with the units used for volume and pressure

Molar gas volume

the volume occupied by one mole of a gas at a given temperature and pressure; at STP, it is 22.41 L

Molar mass

the mass in grams of one mole of a substance (atoms, molecules); its unit is g/mol

Molarity (M)

the number of moles of solute per liter of solution

Mole (mol)

Amount of substance that contains as many molecules or formula units as the number of atoms in exactly 12 g of carbon-12

Molecular formula

Combination of atomic symbols that gives the kinds of atoms and their exact number in a substance

Molecular mass

(= molecular weight) Sum of the atomic masses (weights) of all the atoms in a molecule

Molecules

Tightly bonded groups of two or more atoms of the same or different elements

Noble gases

Group 18 elements

Node

A surface or plane of an orbital where the probability of finding an electron is zero (y2 = 0).

Orbital diagram

is a representation of an electron configuration in which the most probable orbital designation and the spin of each electron in the atom are indicated.

Out

of-phase- said of two waves of the same wavelength that come together with their maxima and minima at opposite points

Overlap

occupation of the same region of space by two orbitals

Paramagnetism

phenomenon whereby substances are weakly attracted to a strong magnetic field because of the presence of unpaired electrons in the substance

Partial pressure

pressure exerted by a particular gas in a gas mixture

Pauli Exclusion Principle

The principle that no two electrons in an atom can have the same set of four quantum numbers n, l, ml, and ms.

Percentage yield

Actual yield of product from a reaction expressed as a percentage of the theoretical yield of product: Percentage yield = actual yield/theoretical yield x 100%

Period (of periodic table)

is a horizontal row of the periodic table.

Periodic law (new form)

When the elements are arranged by atomic number, their physical and chemical properties vary periodically

Periodic law (old form)

When the elements are arranged by atomic mass, their physical and chemical properties vary periodically

Phase

a state of matter (solid, liquid, or gas)

Phase change

change of a substance from one state to another

Photoelectric effect

The emission of electrons from a metallic surface or other material when exposed to light; Einstein explained it by arguing that light behaves as if it were composed of particles

Photon

A quantum of energy