CHEM 1411 FLASHCARDS: Exam #2

Molarity

The number of moles of a substance dissolved in each liter of solution; otherwise known as solution concentration

Molarity is equivalent to…

(Moles of solute)/(Volume of solution (L))

Solution

A homogenous mixture

Solute

The dissolved substance in a solution

Solvent

The major component in a solution

A diluted solution is equivalent to…

Concentrated solution + Solvent (M(i)V(i) = M(f)V(f))

Since the number of moles of solute remains constant, all that changes when adding more solvent is…

The volume of solution

Electrolytes

Substances that dissolve in water to produce conducting solutions of ions; charged particles that conduct electricity; ionic compounds

Nonelectrolytes

Substances that do not produce ions in aqueous solutions; will not dissolve in water or conduct electricity; molecular compounds

Strong Electrolytes

Compounds that dissociate to a large extent into ions when dissolved in water

Weak Electrolytes

Compounds that dissociate to a small extent into ions when dissolved in water

A compound is probably soluble if it contains which of the following cations?

Any group 1A cation (with the exception of hydrogen and francium) or an ammonium ion

A compound is probably soluble if it contains which of the following anions?

Chlorine, bromine, iodine (with the exception of any compounds that contain silver, mercury, or lead), nitrate, perchlorate, acetate, and sulfate (with the exception of any sulfates that contain strontium, barium, mercury, or lead)

What are some examples of strong acids?

Hydrochloric acid, hydrobromic acid, hydroiodic acid, perchloric acid, nitric acid, and sulfuric acid

What are some examples of weak acids?

Acetic acid, hydrofluoric acid, and hydrocyanic acid

What are some example of ionic compounds that are strong electrolytes?

Potassium bromide, sodium chloride, sodium hydroxide, and potassium hydroxide

What are some examples of molecular compounds that are not electrolytes?

Water, methyl alcohol, ethyl alcohol, sucrose, and most compounds of carbon (organic compounds)

Precipitation Reactions

Processes in which soluble reactants yield an insoluble solid product that falls out of solution; double-displacement reactions

Oxidation-Reduction (Redox) Reactions

Processes in which one or more electrons are transferred between reaction partners (atoms, molecules, or ions)

Oxidation

The loss of one or more electrons by a substance, whether element, compound, or ion

Reduction

The gain of one or more electrons by a substance, whether element, compound, or ion

Oxidation Number (State)

A value that indicates whether an atom is neutral, electron-rich, or electron-poor

Oxidizing Agent

Causes oxidation, gains one or more electrons, undergoes reduction, and the oxidation number of the atom decreases

Reducing Agent

Causes reduction, loses one or more electrons, undergoes oxidation, and the oxidation number of the atom increases

In its elemental state, an atom has an oxidation number of…

0

An atom in a monatomic ion has an oxidation number that is…

Identical to its charge

An atom in a polyatomic ion or in a molecular compound usually has the same oxidation number it would have if it were…

A monatomic ion (for example, hydrogen can either be +1 or -1, oxygen usually has an oxidation number of -2, and halogens usually have an oxidation number of -1)

The sum of the oxidation numbers is 0 for a…

Neutral compound

For a polyatomic ion, the sum of the oxidation numbers is equal to its…

Net charge

Acid-Base Neutralization Reactions

Processes in which an acid reacts with a base in order to yield water plus an ionic compound called a salt

Molecular Equation

All substances in the chemical equation are written using their complete formulas as if they were molecules

Ionic Equation

All of the strong electrolytes in the chemical equation are written as ions

Net Ionic Equation

Only the ions undergoing change in the chemical reaction are shown in the chemical equation

Spectator Ions

Ions that undergo no change during the reaction and appear on both sides of the reaction arrow

Acid (Arrhenius)

A substance that dissociates in water in order to produce hydrogen ions

Base (Arrhenius)

A substance that dissociates in water in order to produce hydroxide ions

True or False: Only strong bases are strong electrolytes; strong acids are not

False

True or False: Weak acids and weak bases are weak electrolytes

True

Titration

A procedure used for determining the concentration of a solution by allowing a measured volume of that solution to react with a second solution of another substance (the standard solution) whose concentration is known; once the reaction is complete, you can calculate the concentration of the unknown solution

Elements that are higher up in an activity series are more likely to be…

Oxidized

Any element that is higher in an activity series will ____________ the ion of any element lower in the activity series

Reduce

Electromagnetic energy (“light”) is characterized by…

Wavelength, frequency, and amplitude

Maxima occur for atoms of…

Group 1A elements (Li, Na, K, Rb, Cs, Fr, etc.)

Minima occur for atoms of…

Group 7A elements (F, Cl, Br, I, etc.)

Wavelength

The distance between successive wave peaks

Frequency

The number of wave peaks that pass a given point per unit time

Amplitude

The height of the wave maximum from the center

What we perceive as different kinds of electromagnetic energy are actually…

Waves with different wavelengths and frequencies

Speed is equivalent to…

(Wavelength)(Frequency)

c is defined as…

The rate of travel of all electromagnetic energy in a vacuum; it is a constant value at (3.00)(10^8) that represents the speed of light

Photoelectric Effect

Occurs when irradiation of a clean metal surface with light causes electrons to ejected from the metal; furthermore, the frequency of the light used for the irradiation must be above some threshold value, which is different for every metal

Electromagnetic energy (light) is equivalent to…

(Planck’s constant)(Frequency)

What is Planck’s constant?

(6.626)(10^-34)

True or False: Electromagnetic energy (light) is quantized

True

Electromagnetic radiation consists of particles. What were these later called?

Photons

What experimental observations was Albert Einstein able to make about the photoelectric effect?

No electrons are ejected unless the radiation has a frequency above a certain threshold value that is characteristic of the metal, electrons are ejected immediately, however low the intensity of the radiation, and the kinetic energy of the ejected electrons increases linearly with the frequency of the incident radiation

In 1914, Niels Bohr proposed a model of the hydrogen atom as a…

Nucleus with an electron circling around it

In Bohr’s model, the energy levels of the orbits are ____________ so that only certain specific orbits corresponding to certain specific energies for the electron are available

Quantized

What is Johann Balmer credited for?

Being the first person to identify a pattern in the lines of the visible region of the hydrogen spectrum in 1885

What is Johannes Rydberg credited for?

Presenting an empirical formula for the visible spectral lines of the hydrogen atom in 1885

The Balmer series of spectral lines consists of…

The lines with n(1) = 2 (as well as n(2) = 3, 4, etc.)

The Lyman series of spectral lines consists of…

The lines in the ultraviolet region of the spectrum with n(1) = 1 (as well as n(2) = 2, 3, etc.)

When an electron falls from a higher-energy orbit to a lower-energy orbit, it emits electromagnetic radiation whose ____________ corresponds to the energy difference between the orbits

Frequency

The different spectral series correspond to ____________ from higher-energy to lower-energy orbits

Electron transitions

In 1924, what did Louis de Broglie suggest?

That if light can behave in some respects like matter, then perhaps matter can behave in some respects like light (in other words, perhaps matter is wave-like as well as particle-like)

The de Broglie Equation

Allows the calculation of a “wavelength” of an electron or of any particle or object of mass (m) and velocity (v)

According to the de Broglie equation, wavelength is equivalent to…

(Planck’s constant)/(Mass)(Velocity)

What did Erwin Schrödinger do?

Proposed the quantum mechanical model of the atom, which focuses on the wavelike properties of the electron, in 1926

Heisenberg Uncertainty Principle

States that it is impossible to know precisely where an electron is and what path it follows; created by Werner Heisenberg in 1927

A wave function is characterized by three parameters called…

Quantum numbers (n, l, m(l))

Principal Quantum Number (n)

Describes the size and energy level of the orbital (commonly called a shell); positive integer (1, 2, 3, 4, …); as its value increases, the energy of the electron increases, as well as its average distance from the nucleus

Angular-Momentum Quantum Number (l)

Defines the three-dimensional shape of the orbital (commonly called a sub-shell); there are n different shapes for orbitals (for example, if n = 1, then it is equal to 0, if n = 2, then it is equal to 0 or 1, if n = 3, then it is equal to 0, 1, or 2, etc.); commonly referred to by letter (sub-shell notation) (0 corresponds with s (sharp), 1 corresponds with p (principal), 2 corresponds with d (diffuse), and 3 corresponds with f (fundamental))

Magnetic Quantum Number (m(l))

Defines the spatial orientation of the orbital; there are 2l + 1 values of this number, and they can have any integral value from -l to +l (if l = 0, then it is equal to 0, if l = 1, then it is equal to -1, 0, or 1, if l = 2, then it is equal to -2, -1, 0, 1, or 2 , etc.)

Node

A surface of zero probability for finding the electron

Each p orbital has two lobes of high electron probability separated by a ____________ passing through the nucleus

Nodal plane

Different algebraic signs are analogous to…

Different phases of a wave

Electrons have spin, which gives rise to a tiny magnetic field, as well as a…

Spin quantum number (m(s))

Pauli Exclusion Principle

States that no two electrons in an atom can have the same four quantum numbers

Effective Nuclear Charge (Z(eff))

The nuclear charge actually felt by an electron

Effective nuclear charge is equivalent to…

Z(actual) - Electron shielding

Outer electrons are ____________ toward the nucleus by the nuclear charge

Attracted

Outer electrons are pushed away from the nucleus by the ____________ of inner electrons

Repulsion

Electron Configuration

A description of which orbitals are occupied by electrons

Degenerate Orbitals

Orbitals that have the same energy level - for example, the three p orbitals in a given sub-shell

Ground-State Electron Configuration

The lowest-energy configuration

Aufabu Principle (“building up”)

A guide for determining the filling order of orbitals

True or False: Lower-energy orbitals fill after higher-energy orbitals

False

True or False: An orbital can hold only two electrons, which must have opposite spins

True

True or False: If two or more degenerate orbitals are available, you must follow Hund’s rule

True

Hund’s Rule

States that if two or more orbitals with the same energy are available, one electron goes into each until all are half-full; the electrons in the half-filled orbitals all have the same value of their spin quantum number

Beginning at the top left of the periodic table and moving across successive rows, the order of orbital filling is…

1s → 2s → 2p → 3s → 3p → 4s → 3d → 4p and so on

Ground-state electron configurations can be written three different ways. What are these three possible notations?

Orbital notation (orbital filling diagram), simplified notation, and noble-gas based notation

Valence Shell

Outermost shell

As ____________ increases, the valence shell electrons are attracted more strongly to the nucleus

Effective nuclear charge

As effective nuclear charge increases, the ____________ decreases

Atomic radius

Ionization Energy (E(i))

The amount of energy needed in order to remove the highest-energy electron from an isolated neutral atom in the gaseous state

____________ are smaller than the corresponding neutral atoms

Cations

____________ are larger than their neutral atoms

Anions

Why are anions larger than their corresponding neutral atoms?

Because of additional electron-electron repulsions and a decrease in effective nuclear charge

Why are cations smaller than their corresponding neutral atoms?

Because the principal quantum number of the valence-shell electrons is smaller than it is for the neutral atoms and because effective nuclear charge is larger