CHEM2077: Chemistry of the Elements - Lecture 1 Flashcards

Vocabulary flashcards covering core concepts, periodic trends, and shielding rules from CHEM2077 Lecture 1.

Wavefunction ($\Psi$)

A mathematical expression for the "height" of the electron wave, defined by four quantum numbers: $n$ (principal), $l$ (angular momentum), $m_l$ (magnetic), and $m_s$ (spin).

Born Interpretation

The interpretation stating that $\Psi^2$ gives the probability of finding an electron at a specific point.

Radial Distribution Function (RDF)

Represents the probability of finding an electron at a given radius $r$ from the nucleus in all directions.

Effective Nuclear Charge ($Z_{eff}$)

The net positive charge experienced by an electron in a multi-electron atom, calculated as $Z_{eff} = Z - S$, where $S$ is the shielding constant.

Shielding/Screening

The process where outer electrons are protected from the full nuclear charge ($Z$) by filled inner electron shells.

Slater’s Rule for $(n)$ shell

According to Slater’s rules, the shielding constant $S = 0.35$ for electrons in the same shell.

Slater’s Rule for $(n-1)$ shell

According to Slater’s rules, the shielding constant $S = 0.85$ for electrons in the $(n-1)$ shell.

Slater’s Rule for $(n-2)$ shells

According to Slater’s rules, the shielding constant $S = 1.00$ for electrons in $(n-2)$ shells and deeper.

Penetration

The ability of an orbital to approach the nucleus more closely; for example, Lithium ($3Li$) $2s$ electrons penetrate the $1s$ orbital better than $2p$ electrons do, feeling a higher $Z_{eff}$.

d-block contraction (Alternation Effect)

An effect in Group 13 where Ga ($122\,pm$) is smaller than Al ($143\,pm$) because the $3d^{10}$ electrons are poor at shielding, causing $Z_{eff}$ to increase and the radius to decrease.

Ionization Energy (IE)

The energy required to remove an electron from a gas-phase atom.

Electronegativity ($\chi$)

The tendency of an atom in a molecule to attract electrons to itself.

Metallic Character

Properties associated with elements in the bottom-left of the periodic table, characterized by low $\chi$, formation of cations, and metallic bonding with delocalized electrons.

Non-metallic Character

Properties associated with elements in the top-right of the periodic table, characterized by high $\chi$, high electron affinity, formation of anions, and covalent bonding.

Metalloids

Elements found in the center of the p-block that exhibit intermediate metallic and non-metallic properties.

Non-polar covalent Bond

A bond type predicted when the difference in electronegativity ($\Delta\chi$) is between $0$ and $0.5$ (e.g., $H_2$, $CH_4$).

Polar covalent Bond

A bond type predicted when the difference in electronegativity ($\Delta\chi$) is between $0.5$ and $1.8$ (e.g., $H_2O$, $HF$).

Ionic Bond

A bond type predicted when the difference in electronegativity ($\Delta\chi$) is greater than $2.0$ (e.g., $NaCl$, $CsF$).

Thermodynamic Relation for Potential

The relationship between Gibbs free energy and cell potential expressed as $\Delta G = -nFE^\circ$.