Orbital Filling Rules and Electron Configuration

Vocabulary flashcards covering orbital diagram rules, electron configurations, subshell energy levels, period relationships, valence electrons, and Lewis symbols.

Orbital Diagram

A visual representation showing the filling of orbitals with electrons at each subshell, where lines represent orbitals holding up to $2$ electrons and arrows represent electrons indicating their spin directions.

Electron Configuration

A notation showing the distribution of electrons among subshells, consisting of the principal quantum number $n$, the symbol of the subshell, and a superscript indicating the number of electrons in that subshell.

Orbital Filling Rule 1

The rule stating that electrons always occupy the lowest energy orbitals first, filling orbitals from least energy to greatest.

Orbital Filling Rule 2

The rule specifying a limit of $2$ electrons per orbital, which must have opposite spins.

Orbital Filling Rule 3

The rule stating that single electrons must occupy all orbitals of a subshell before pairing of electrons occurs.

Subshell Energy Order

The relative energy order of subshells within the same shell ($s < p < d < f$), where a lower subshell of a higher shell can have lower energy than a higher subshell of a lower shell (such as $4s$ being filled before $3d$).

Subshell Period Number Rules

Rules that determine the quantum shell $n$ being filled from the periodic table: $n = \text{period number}$ for $s$ and $p$ subshells, $n = \text{period number} - 1$ for $d$ subshells, and $n = \text{period number} - 2$ for $f$ subshells.

Abbreviated Electron Configuration

A simplified electron configuration created by substituting the inner-shell electron configuration with the atomic symbol of the preceding noble gas in brackets, such as $[\text{Kr}]5s^2 4d^{10} 5p^5$.

Valence Shell

The outermost occupied electron shell of an atom, defined as the shell having the highest principal quantum number $n$.

Valence Electrons

Electrons that occupy the valence shell (highest $n$ value for $s + p$ subshells), which equal the group A number for main group elements and range between $1$ and $8$.

Core Electrons

All non-valence electrons in an atom that occupy inner subshells with lower principal quantum numbers $n$.

Lewis (Electron-Dot) Symbols

Representations of main group elements where valence electrons are shown as dots surrounding the atomic symbol, placing the first $4$ dots unpaired before pairing the next $4$ dots.