CHE 105 Exam 3 Study Guide

Comprehensive Question and Answer flashcard set covering vocabulary, concepts, formulas, equations, quantum number rules, subshell capacities, and constants for Exam 3.

What is the photoelectric effect?

The release of electrons from a material when light shines on it.

What are photoelectrons?

Electrons emitted from a material during the photoelectric effect.

What are photons?

Packets, or individual units, of light energy.

What is the work function?

The minimum energy needed to remove an electron from a material.

What is the threshold frequency?

The minimum frequency of light needed to cause the photoelectric effect.

What is wavelength?

The distance between matching points on consecutive waves.

What is frequency?

The number of wave cycles that pass a point each second.

What is the electromagnetic spectrum?

The full range of electromagnetic radiation, arranged by wavelength or frequency.

What is the Bohr model?

A model of the atom in which electrons occupy specific energy levels.

What are atomic line spectra?

A pattern of specific wavelengths of light emitted or absorbed by an atom.

What is the ground state?

The lowest energy state of an atom or electron.

What is an excited state?

A state in which an atom or electron has more energy than in its ground state.

What is the Rydberg constant?

A constant used in equations that describe the wavelengths of light associated with hydrogen energy-level changes.

What is covalent bonding?

Bonding in which atoms share electrons.

What is electronegativity?

A measure of an atom's ability to attract shared electrons in a chemical bond.

What is a pure covalent bond?

A covalent bond in which electrons are shared equally.

What is a polar covalent bond?

A covalent bond in which electrons are shared unequally.

What is an ionic bond?

The attraction between oppositely charged ions.

What defines a nonpolar covalent bond or molecule?

A bond or molecule with an even distribution of electron density.

What defines a polar covalent bond or molecule?

A bond or molecule with an uneven distribution of electron density.

What does the term ionic describe?

Describes a bond or compound involving oppositely charged ions.

What is metallic character?

How strongly an element shows the typical properties of metals.

What are metals?

Elements that generally conduct heat and electricity, are malleable, and tend to lose electrons.

What are nonmetals?

Elements that generally conduct heat and electricity poorly and tend to gain or share electrons.

What are metalloids?

Elements with properties between those of metals and nonmetals.

What causes ionic bonding?

Bonding caused by the electrostatic attraction between cations and anions.

What is metallic bonding?

Bonding in metals involving positive metal ions attracted to delocalized electrons.

What are cations and anions?

Cations are positively charged ions, and anions are negatively charged ions.

What are ionic compounds?

Compounds made of cations and anions.

What is a chemical formula?

A combination of element symbols and subscripts showing the types and relative numbers of atoms or ions in a substance.

What is a Lewis dot symbol?

An element symbol surrounded by dots representing its valence electrons.

What is the octet rule?

The tendency of atoms to gain, lose, or share electrons to reach eight valence electrons.

What are lone pairs?

Pairs of valence electrons that are not shared in a bond.

What is a Lewis structure?

A diagram showing valence electrons and bonds in a molecule or ion.

What is the difference between single, double, and triple bonds?

A single bond shares one pair of electrons, a double bond shares two pairs of electrons, and a triple bond shares three pairs of electrons.

What are free radicals?

Species with one or more unpaired electrons.

What are incomplete octets and expanded octets?

Incomplete octets are cases in which an atom has fewer than eight electrons around it in a Lewis structure, while expanded octets are cases where an atom is shown with more than eight electrons around it.

What are orbital diagrams?

Drawings that show electrons occupying individual orbitals, using arrows to represent electrons.

What are degenerate orbitals?

Orbitals that have the same energy.

What is the Aufbau principle (building-up principle)?

Electrons fill the lowest-energy orbitals available before higher-energy orbitals.

What is the Pauli exclusion principle?

No two electrons in an atom can have the same set of four quantum numbers; an orbital holds at most two electrons with opposite spins.

What is Hund's rule?

Electrons occupy orbitals of equal energy one at a time, with parallel spins, before pairing.

What is an electron configuration?

A notation showing how an atom's electrons are distributed among orbitals.

What is the difference between paramagnetic and diamagnetic substances?

Paramagnetic describes a substance with unpaired electrons that is attracted to a magnetic field, while diamagnetic describes a substance with all electrons paired that is weakly repelled by a magnetic field.

What are valence electrons?

The electrons in the outermost occupied shell that are most involved in bonding.

What is a noble gas?

An element in Group 18, generally known for having a filled valence shell.

What are anomalous electron configurations?

Electron configurations that differ from the expected filling order, often because nearby arrangements have similar energies.

What does the term isoelectronic mean?

Describes atoms or ions that have the same number of electrons.

What is electron density?

A measure of the probability of finding an electron in a particular region of space.

What is quantum mechanics?

The branch of physics used to describe the behavior of very small particles, such as electrons.

What are atomic orbitals?

Regions around the nucleus described by quantum mechanics where an electron is likely to be found.

What are quantum numbers?

Numbers that describe an electron's energy, orbital shape, orbital orientation, and spin.

What is the principal quantum number ($n$)?

The quantum number that identifies an electron's main energy level and is related to orbital size.

What is the angular momentum quantum number ($\ell$)?

The quantum number that identifies an orbital's subshell and shape.

What is the magnetic quantum number ($m_\ell$)?

The quantum number that identifies an orbital's orientation.

What is the spin quantum number ($m_s$)?

The quantum number that describes an electron's spin; it can be $+\frac{1}{2}$ or $-\frac{1}{2}$.

What is an orbital lobe?

A rounded region of an orbital, such as one of the two regions in a p orbital.

What is ionization energy?

The energy required to remove an electron from a gaseous atom or ion.

What is electron affinity?

The energy change that occurs when a gaseous atom gains an electron.

What are core electrons?

Electrons that are not in the outermost occupied shell and generally do not participate in bonding.

What is periodicity?

The repeating pattern of element properties across the periodic table.

What is atomic radius?

A measure of the size of an atom, commonly based on distances between nuclei.

What is the difference between metallic radius and covalent radius?

Metallic radius is half the distance between the nuclei of two neighboring metal atoms in a metallic solid, while covalent radius is half the distance between the nuclei of two identical atoms joined by a covalent bond.

What is effective nuclear charge?

The net positive charge experienced by an electron after accounting for shielding by other electrons.

What is the de Broglie wavelength?

The wavelength associated with a moving particle.

What is the Heisenberg uncertainty principle?

The principle that the position and momentum of a particle cannot both be known with unlimited precision at the same time.

What are the formulas for photon energy and the wave relationship?

Photon energy: $E = h\nu$; Wave relationship: $\nu\lambda = c$.

What are the equations for threshold energy and threshold wavelength?

Threshold energy: $h\nu = \Phi$ and $\frac{hc}{\lambda} = \Phi$; Threshold wavelength: $\lambda = \frac{hc}{\Phi}$.

What is the equation for photoelectron kinetic energy?

$$KE = h\nu - \Phi$$

What is the Rydberg equation for hydrogen spectra?

$\frac{1}{\lambda} = R_\infty \left(\frac{1}{n_1^2} - \frac{1}{n_2^2}\right)$, where $n_2 > n_1$.

What is the equation for the energy of a hydrogen energy level?

$$E = -2.18 \times 10^{18}\,\text{J}\left(\frac{1}{n^2}\right)$$

What is the formula for the energy of an electron transition ($\Delta E$)?

$\Delta E = h\nu = -2.18 \times 10^{18}\,\text{J}\left(\frac{1}{n_f^2} - \frac{1}{n_i^2}\right)$ or $\Delta E = h\nu = -R_H\left(\frac{1}{n_f^2} - \frac{1}{n_i^2}\right)$, where $R_H = 2.18 \times 10^{18}\,\text{J}$.

What is the formula for the wavelength of a transition?

$$\frac{1}{\lambda} = \left(\frac{2.18 \times 10^{18}\,\text{J}}{hc}\right)\left(\frac{1}{n_f^2} - \frac{1}{n_i^2}\right)$$

What is the formula for Coulomb's law?

$$F = \frac{k q_1 q_2}{r^2}$$

What is the formula for effective nuclear charge ($Z_{\text{eff}}$), and what are the calculations for Carbon and Calcium?

Formula: $Z_{\text{eff}} = Z - S$; Carbon: $Z_{\text{eff}} = 6 - 2 = 4$; Calcium: $Z_{\text{eff}} = 20 - 18 = +2$.

What are the chemical reaction equations for the first, second, and third ionizations?

First ionization: $M(g) \rightarrow M(g) + e$; Second ionization: $M(g) \rightarrow M^2(g) + e$; Third ionization: $M^2(g) \rightarrow M^3(g) + e$.

What is the chlorine electron affinity reaction and its enthalpy change?

$Cl(g) + e \rightarrow Cl(g)$, $\Delta H = -348.6\,\text{kJ/mol}$

What are the mathematical formulations for the de Broglie wavelength and Heisenberg uncertainty principle?

de Broglie wavelength: $\lambda = \frac{h}{mv}$; Heisenberg uncertainty principle: $\Delta x \Delta p \ge \frac{h}{4\pi}$ and $\Delta x \cdot m\Delta v \ge \frac{h}{4\pi}$.

What are the allowed values for the four quantum numbers?

Principal: $n = 1, 2, 3, \dots$; Angular momentum: $\ell = 0, 1, 2, \dots, n - 1$; Magnetic: $m_\ell = -\ell, \dots, 0, \dots, +\ell$; Spin: $m_s = +\frac{1}{2}\text{ or } -\frac{1}{2}$.

What are the number of orbitals and maximum electron capacities for subshells s, p, d, and f?

Subshell s: $1$ orbital, $2$ electrons; Subshell p: $3$ orbitals, $6$ electrons; Subshell d: $5$ orbitals, $10$ electrons; Subshell f: $7$ orbitals, $14$ electrons.

What are the values of Planck's constant ($h$), the speed of light ($c$), and the Rydberg constant ($R_\infty$)?

Planck's constant: $h = 6.626 \times 10^{34}\,\text{J}\cdot\text{s}$; Speed of light: $c = 2.998 \times 10^8\,\text{m/s}$; Rydberg constant: $R_\infty = 1.09737317 \times 10^7\,\text{m}^1$.