General Chemistry: Atomic Structure, Periodic Trends, and Chemical Bonding

Flashcards covering atomic structure, quantum mechanics, electron configurations, periodic trends, and chemical bonding concepts.

How are wavelength ($\lambda$), frequency ($\nu$), and the speed of light ($c$) related, and what is the exact constant value of $c$ in a vacuum?

$c = \nu \times \nu$, where the speed of light in a vacuum is $c = 2.99792458 \times 10^8\,\text{m/s}$.

According to Max Planck, what is a quantum, and what equation gives the energy of one quantum of electromagnetic radiation?

A quantum is the smallest discrete quantity of a particular form of energy, given by $E = h\nu$, where Planck's constant is $h = 6.62607015 \times 10^{-34}\,\text{J}\cdot\text{s}$.

What two distinct yellow wavelengths are emitted in the atomic emission spectrum of sodium in a flame?

$589.0\,\text{nm}$ and $589.6\,\text{nm}$.

In the photoelectric effect, what equation defines the kinetic energy ($KE$) of an ejected electron?

$KE = h\nu - \Phi$, where $h\nu$ is the photon energy and $\Phi$ is the binding energy (or work function) corresponding to the threshold frequency ($\nu_0$).

In the hydrogen atom emission spectrum shown, which series corresponds to electronic transitions falling to the $n = 2$ level and produces visible light?

The Balmer series.

What are the four visible line wavelengths observed in the Balmer series of the hydrogen emission spectrum?

$656\,\text{nm}$, $486\,\text{nm}$, $434\,\text{nm}$, and $410\,\text{nm}$.

What is the energy value ($E_1$) of the ground state ($n = 1$) level in Niels Bohr's model of the hydrogen atom?

$E_1 = -2.18 \times 10^{-18}\,\text{J}$.

What is the de Broglie equation relating the wavelength of a moving particle to its mass and velocity?

$\lambda = \frac{h}{mv}$, where $m$ is mass in $\text{kg}$ and $v$ is velocity in $\text{m/s}$.

What is the mathematical formulation of Heisenberg's uncertainty principle for an electron?

$(\Delta x)(m\Delta v) \ge \frac{h}{4\pi}$.

Based on this $1s$ radial distribution function, at what distance from the nucleus is the total radial probability maximized?

$52.9\,\text{pm}$.

What does each of the four quantum numbers ($n$, $l$, $m_l$, and $m_s$) describe?

$n$ (principal) defines energy level and size; $l$ (angular momentum) defines orbital shape ($s, p, d, f$); $m_l$ (magnetic) defines orbital orientation; $m_s$ (spin magnetic) defines the electron spin ($+\frac{1}{2}$ or $-\frac{1}{2}$).

How many total orbitals exist in a principal energy level $n$?

$n^2$ orbitals.

What experiment is shown in this diagram, which proved electron spin quantization by splitting a beam of silver atoms in an inhomogeneous magnetic field?

The Stern–Gerlach Experiment.

What does the Pauli exclusion principle state regarding electron quantum numbers?

No two electrons in an atom may have the same set of four quantum numbers ($n$, $l$, $m_l$, and $m_s$).

What is the Aufbau principle?

As protons are added one by one to the nucleus to build up the elements, electrons are added to hydrogen-like orbitals from lowest energy to highest energy.

What is Hund's rule?

The lowest energy (most stable) 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.

What are the anomalous ground-state electron configurations of Chromium ($\text{Cr}$) and Copper ($\text{Cu}$)?

$\text{Cr}$ is $[\text{Ar}]4s^1 3d^5$ and $\text{Cu}$ is $[\text{Ar}]4s^1 3d^{10}$, because half-filled and completely filled degenerate $d$ orbitals are energetically favored.

When transition metal atoms such as Iron ($\text{Fe}$) form cations, from which subshell are electrons removed first?

Electrons are removed from the valence $4s$ orbital first before any $3d$ electrons are lost (e.g., $\text{Fe}^{3+}$ is $[\text{Ar}]3d^5$).

What is the difference between paramagnetism and diamagnetism in terms of electron configuration?

Paramagnetic substances contain unpaired electrons and are attracted to an external magnetic field; diamagnetic substances contain only paired electrons and experience no net attraction.

What are the general periodic trends for atomic radius across a period and down a group?

Atomic radius decreases from left to right across a period (due to increasing $Z_{\text{eff}}$) and increases from top to bottom down a group (due to adding electron shells).

How do the sizes of cations and anions compare to their parent neutral atoms?

A cation is always smaller than its parent atom, whereas an anion is always larger than its parent atom.

What accounts for the discontinuity in first ionization energy between Group 2A ($\text{Be}$) and Group 3A ($\text{B}$)?

Removing an electron from Boron involves a $2p$ orbital electron, which exhibits less orbital penetration and is shielded by the $2s$ electrons, making it easier to remove than a $2s$ electron in Beryllium.

What causes the discontinuity in first ionization energy between Group 5A ($\text{N}$) and Group 6A ($\text{O}$)?

In Oxygen, an electron is removed from a doubly occupied $2p$ orbital where two electrons share the same orbital and repel each other, lowering the energy required for removal.

Why is there an abrupt, massive increase in successive ionization energies for an element after all its valence electrons are removed?

Because removing subsequent electrons requires taking core electrons from a fully filled, stable inner shell that is much closer to the nucleus.

What actual atomic mass and density did Gallium (eka-aluminum) exhibit compared to Mendeleev's predictions?

Mendeleev predicted an atomic mass of about $68\,\text{amu}$ and a density of $5.9\,\text{g/cm}^3$; the actual properties of Gallium are $69.72\,\text{amu}$ and $5.90\,\text{g/cm}^3$.

What are the three major categories of chemical bonds, and how do their valence electrons behave?

Covalent bonding (sharing of electrons between nonmetals), ionic bonding (electrostatic attraction between oppositely charged ions formed by electron transfer), and metallic bonding (a 'sea' of delocalized electrons shared among metal nuclei).

What is lattice energy in an ionic solid?

The enthalpy change associated with the condensation of gaseous ions into a crystalline ionic solid (e.g., $\text{Na}^+(g) + \text{Cl}^-(g) \rightarrow \text{NaCl}(s)$).

How does ion charge affect the magnitude of lattice energy, as illustrated by comparing $\text{NaCl}$ and $\text{CaO}$?

Larger ion charges result in much stronger electrostatic attractions and far more exothermic lattice energies (e.g., $\text{CaO}$ with $2+$ and $2-$ ions has $\Delta H^\circ_{\text{lattice}} = -3414\,\text{kJ/mol}$, compared to $-787\,\text{kJ/mol}$ for $\text{NaCl}$).

According to Table 9.1 shown, what bond type corresponds to an intermediate electronegativity difference ($\Delta\text{EN}$) of $0.4\text{–}2.0$?

Polar covalent bond.

What is the dipole moment formula, and how is the Debye ($\text{D}$) unit defined in SI units?

$\mu = Q \times r$, where $1\,\text{D} = 3.34 \times 10^{-30}\,\text{C}\cdot\text{m}$.

How is percent ionic character calculated, and what threshold classifies a bond as predominantly ionic?

$\text{Percent ionic character} = \frac{\text{actual } \mu}{\mu \text{ if electrons were completely transferred}} \times 100\%$, where a value greater than $50\%$ is classified as ionic.

What monomer and resulting polymer, commonly used in plumbing pipe fittings, are illustrated in this diagram?

Chloroethene (monomer) and Polyvinyl chloride (PVC) (polymer).

What are three examples of synthetic commercial polymers and their stated primary uses?

Polyethylene (films, packaging, bottles), Polystyrene (packaging, disposable food containers, insulation), and Nylon 6,6 (home furnishings, carpet fibers, fish line).