General Chemistry: Atomic Theory, Quantum Mechanics, Periodic Trends, and Chemical Bonding

Comprehensive flashcard deck covering fundamental chemistry topics including atomic theory, quantum mechanics, wavefunctions, periodic trends, stoichiometry, redox reactions, hydrogen chemistry, and bonding models.

What are the three fundamental mass laws accounted for by Dalton's atomic model?

The law of conservation of mass, the law of constant composition (definite proportions), and the law of multiple proportions.

Which experiment allowed Robert Millikan to measure the charge of an electron, and what magnitude was determined?

The oil drop experiment, which measured the magnitude of the electron charge as $q = 1.6 \times 10^{-19}\text{ C}$.

What key observation in the 1909 Rutherford gold foil experiment led to the rejection of Thomson's plum pudding model?

A small fraction of alpha ($\text{α}$) particles were deflected at large angles or scattered backwards, demonstrating that the atom contains a tiny, dense, positively charged nucleus.

What is the mass of $1\text{ amu}$ expressed in grams?

$1\text{ amu} = 1.66 \times 10^{-24}\text{ g}$.

What defines two atoms as isotopes of the same element?

They have the same atomic number ($Z$, number of protons) but different mass numbers ($A$) because they contain a different number of neutrons.

How is the atomic mass of naturally occurring carbon calculated from its isotopic abundances ($98.892\%$ $^{12}\text{C}$ with mass $12\text{ amu}$ exactly; $1.108\%$ $^{13}\text{C}$ with mass $13.00335\text{ amu}$)?

$\text{Atomic Mass} = 0.98892(12\text{ amu}) + 0.01108(13.00335\text{ amu}) = 12.011\text{ amu}$.

How do the names of oxyacids change based on the suffix of their corresponding oxoanion?

Oxoanions ending in "-ate" produce acids ending in "-ic acid", whereas oxoanions ending in "-ite" produce acids ending in "-ous acid".

What is the oxidation state of hydrogen when bonded to nonmetals versus when bonded to Group 1 or Group 2 metals?

Hydrogen has an oxidation state of $+1$ when bonded to nonmetals (covalent hydrides) and $-1$ when bonded to Group 1 or Group 2 metals (ionic hydrides).

What equation relates the speed of light ($c$), wavelength ($\lambda$), and frequency ($\nu$) in a vacuum?

$c = \lambda \nu$, where $c = 2.998 \times 10^8\text{ m\,s}^{-1}$.

What equation gives the energy ($E$) of a single photon of light in terms of its frequency ($\nu$) or wavelength ($\lambda$)?

$E = h\nu = \frac{hc}{\lambda}$, where Planck's constant $h = 6.626 \times 10^{-34}\text{ J\,s}$.

According to quantum theory, what property of incoming light determines whether electrons are ejected from a metal surface in the photoelectric effect?

The frequency ($\nu$) of the light, which must meet or surpass the threshold frequency ($\nu_0$) corresponding to the work function ($\Phi$) of the metal.

What formula describes the visible emission lines (Balmer series) of the hydrogen atom spectrum?

$\frac{1}{\lambda} = R_H \left(\frac{1}{2^2} - \frac{1}{n^2}\right)$, where $n = 3, 4, 5, 6, \dots$ and $R_H = 1.097 \times 10^7\text{ m}^{-1}$.

What is the formula for the energy of an electron in a stationary state $n$ of a hydrogen-like species according to the Bohr model?

$E_n = -R_H \frac{Z^2}{n^2}$, where $R_H = 2.179 \times 10^{-18}\text{ J}$ and $Z$ is the nuclear charge.

What is the de Broglie equation relating the wavelength ($\lambda$) of a particle to its momentum ($p$)?

$\lambda = \frac{h}{p} = \frac{h}{m v}$.

What experimental evidence confirmed the wavelike behavior of electrons proposed by de Broglie?

The observation of electron diffraction patterns when a beam of electrons is passed through a crystalline aluminum target, resembling X-ray diffraction patterns.

How is the Heisenberg Uncertainty Principle expressed mathematically for position ($\Delta x$) and momentum ($\Delta p$)?

$\Delta x \cdot \Delta p \ge \frac{h}{4\pi}$.

What are the four quantum numbers that describe an electron in an atom and their physical interpretations?

1. Principal quantum number ($n$: size and energy of orbital)
2. Angular momentum quantum number ($l$: shape of orbital)
3. Magnetic quantum number ($m_l$: spatial orientation of orbital)
4. Spin quantum number ($m_s$: direction of electron spin)

How are the numbers of radial nodes, angular nodes, and total nodes calculated for an orbital defined by quantum numbers $n$ and $l$?

Radial nodes $= n - l - 1$, angular nodes $= l$, and total nodes $= n - 1$.

How does orbital energy degeneracy differ between a one-electron atom (such as $\text{H}$) and a many-electron atom?

In a one-electron atom, all orbitals within the same principal shell (same $n$) are degenerate. In a many-electron atom, only orbitals within the same subshell (same $n$ and $l$) are degenerate.

Why is a $2s$ orbital lower in energy than a $2p$ orbital in a many-electron atom?

The $2s$ orbital penetrates closer to the nucleus due to a radial probability peak near the nucleus, experiencing a higher effective nuclear charge ($Z_{eff}$) and less shielding.

What does the Pauli exclusion principle state regarding the quantum numbers of electrons in an atom?

No two electrons in an atom can have the exact same set of all four quantum numbers ($n, l, m_l, m_s$); thus, an orbital can hold a maximum of two electrons with opposing spins.

What is Hund's rule regarding the filling of degenerate orbitals?

When orbitals of equal energy are available, electrons occupy them singly with parallel spins before pairing up.

What are the anomalous ground-state electron configurations of chromium ($\text{Cr}$, $Z=24$) and copper ($\text{Cu}$, $Z=29$)?

Chromium is $[\text{Ar}] 4s^1 3d^5$ and copper is $[\text{Ar}] 4s^1 3d^{10}$.

Which electrons are lost first when a transition-metal atom forms a cation?

The $ns$ electrons are removed before the $(n-1)d$ electrons.

How do paramagnetic and diamagnetic substances differ in electron configuration and magnetic behavior?

Paramagnetic substances contain one or more unpaired electrons and are weakly attracted by a magnetic field; diamagnetic substances have all electrons paired and are weakly repelled by a magnetic field.

Why are cations smaller than their neutral parent atoms, while anions are larger than their neutral parent atoms?

Cations lose outer valence electrons, increasing $Z_{eff}$ felt by remaining electrons and reducing repulsion. Anions gain electrons, increasing electron-electron repulsion and expanding the electron cloud.

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

Atomic radius decreases across a period (due to increasing $Z_{eff}$) and increases down a group (due to increasing principal shell $n$).

What are the general periodic trends for first ionization energy ($IE_1$)?

First ionization energy increases across a period and decreases down a group.

What causes a sudden large jump between successive ionization energies of an element?

A large jump occurs when all valence electrons have been removed and the next electron must be removed from a stable inner core shell.

How are reducing agents and oxidizing agents defined in terms of electron transfer and change in oxidation state?

A reducing agent loses electrons (is oxidized), causing its oxidation state to increase; an oxidizing agent gains electrons (is reduced), causing its oxidation state to decrease.

How do metal oxides and nonmetal oxides differ in their reactions with water?

Metal oxides are basic oxides (react with water to form metal hydroxides), whereas nonmetal oxides are acidic oxides (react with water to form oxyacids).

What are the two main industrial processes for producing hydrogen gas ($\text{H}_2$)?

The water-gas shift reaction ($\text{CO}(g) + \text{H}_2\text{O}(g) \rightarrow \text{CO}_2(g) + \text{H}_2(g)$) and steam-hydrocarbon reforming ($\text{CH}_4(g) + \text{H}_2\text{O}(g) \rightarrow \text{CO}(g) + 3\text{H}_2(g)$).

What chemical equation represents the Haber-Bosch process for ammonia synthesis?

$\text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g)$.

What are the three classes of hydrides formed by hydrogen across the periodic table?

1. Covalent hydrides (with nonmetals; H in $+1$ oxidation state)
2. Ionic hydrides (with Group 1 and 2 metals; H in $-1$ oxidation state)
3. Metallic/interstitial hydrides (with transition metals)

How is sodium metal extracted industrially from sodium chloride?

Via electrolysis of molten sodium chloride in a Downs cell: $2\text{NaCl}(l) \rightarrow 2\text{Na}(l) + \text{Cl}_2(g)$.

According to Coulomb's Law, what parameters determine the magnitude of lattice energy in an ionic crystal?

Lattice energy is directly proportional to the product of ionic charges ($|q_1 q_2|$) and inversely proportional to the distance between ion centers ($d$).

Why are ionic solids characteristically brittle when struck by a hammer?

Applied external force shifts layers of ions so that ions of like charge align directly beside each other; the strong electrostatic repulsion causes the crystal lattice to crack.

How does the electron sea model explain the malleability and electrical conductivity of metals?

Metal cations are immersed in delocalized, mobile valence electrons. These electrons flow easily under an applied potential to conduct electricity and allow metal ion cores to slide past one another without repelling or shattering.

How is the standard enthalpy of reaction ($\Delta H_{rxn}^\circ$) calculated from average bond energies ($BE$)?

$\Delta H_{rxn}^\circ = \sum BE(\text{bonds broken}) - \sum BE(\text{bonds formed})$.

Why do fats (such as triolein) yield more energy per gram upon combustion than carbohydrates (such as sucrose)?

Fats are more chemically reduced, containing a higher ratio of $\text{C}-\text{H}$ and $\text{C}-\text{C}$ bonds and fewer $\text{C}-\text{O}$ bonds than carbohydrates.

What is the relative order of electronegativity among common nonmetal elements according to the Pauling scale?

$\text{F} > \text{O} > \text{Cl}, \text{N} > \text{Br} > \text{I}, \text{C}, \text{S} > \text{H}$.

What formula calculates the formal charge on an atom in a Lewis structure?

$\text{Formal Charge} = (\text{valence } e^- \text{ in free atom}) - (\text{lone pair } e^-) - \frac{1}{2}(\text{bonding } e^-)$.

What are the three main exceptions to the octet rule in Lewis structures?

1. Odd-electron species (free radicals, e.g., $\text{NO}$).
2. Incomplete octets ($\text{Be}$, $\text{B}$, or $\text{Al}$ compounds, e.g., $\text{BF}_3$).
3. Expanded valence shells (period 3 or heavier central elements with 10 or 12 electrons, e.g., $\text{ClF}_3$, $\text{POCl}_3$).