Long Form of the Periodic Table and Modern Periodic Law

Critical vocabulary and historical context regarding the development of the modern periodic table, Moseley's Law, and period-by-period electronic configurations.

Mendelevium ($Md$)

Element with atomic number $Z = 101$, originally assigned the IUPAC symbol $Unu$ (Unnilunium).

Nobelium ($No$)

Element with atomic number $Z = 102$, originally assigned the IUPAC symbol $Unb$ (Unnilbium).

Lawrencium ($Lr$)

Element with atomic number $Z = 103$, originally assigned the IUPAC symbol $Unt$ (Unniltrium).

Rutherfordium ($Rf$)

Element with atomic number $Z = 104$, originally assigned the IUPAC symbol $Unq$ (Unnilquadium).

Dubnium ($Db$)

Element with atomic number $Z = 105$, originally assigned the IUPAC symbol $Unp$ (Unnilpentium).

Seaborgium ($Sg$)

Element with atomic number $Z = 106$, originally assigned the IUPAC symbol $Unh$ (Unnilhexium).

Bohrium ($Bh$)

Element with atomic number $Z = 107$, originally assigned the IUPAC symbol $Uns$ (Unnilseptium).

Hassium ($Hs$)

Element with atomic number $Z = 108$, originally assigned the IUPAC symbol $Uno$ (Unniloctium).

Meitnerium ($Mt$)

Element with atomic number $Z = 109$, originally assigned the IUPAC symbol $Une$ (Unnilennium).

Darmstadtium ($Ds$)

Element with atomic number $Z = 110$, originally assigned the IUPAC symbol $Uun$ (Ununilium).

Roentgenium ($Rg$)

Element with atomic number $Z = 111$, originally assigned the IUPAC symbol $Uuu$ (Unununium).

Copernicium ($Cn$)

Element with atomic number $Z = 112$, originally assigned the IUPAC symbol $Uub$ (Ununbium).

Flerovium ($Fl$)

Element with atomic number $Z = 114$, originally assigned the IUPAC symbol $Uuq$ (Ununquadium).

Livermorium ($Lv$)

Element with atomic number $Z = 116$, originally assigned the IUPAC symbol $Uuh$ (Ununhexium).

Moseley's Discovery (1913)

Showed that the atomic number is a more fundamental property of an element than its atomic mass, using X-ray frequency analysis.

Moseley's Mathematical Relation

$\sqrt{\nu} = a(Z - b)$, where $\nu$ is the frequency of X-rays, $Z$ is the nuclear charge (atomic number), and $a$ and $b$ are constants.

Modern Periodic Law

The principle stating that "the physical and chemical properties of elements are periodic functions of their atomic numbers."

Groups

The $18$ vertical columns in the long form of the periodic table.

Periods

The $7$ horizontal rows in the long form of the periodic table.

Alkali Metal Starting Configuration

The outermost electronic configuration $ns^{1}$ that marks the start of each period.

Noble Gas Ending Configuration

The outermost electronic configuration $ns^{2} np^{6}$ (except for $He$ which is $1s^{2}$) that marks the end of each period.

Principal Quantum Number ($n$)

The quantum number that defines the main energy levels of the shell, such as $n = 1$ for the 1st period.

Period-1 (Shortest period)

Corresponds to filling the $K$-shell ($n = 1$); contains $2$ elements: $H$ ($1s^{1}$) and $He$ ($1s^{2}$).

Period-2 (First short period)

Corresponds to filling the $L$-shell ($n = 2$) using $2s$ and $2p$ orbitals; contains $8$ elements from Lithium to Neon.

Period-3 (Second short period)

Corresponds to filling the $M$-shell ($n = 3$) using $3s$ and $3p$ orbitals; contains $8$ elements from $Na$ to $Ar$.

Period-6 Capacity

Contains $32$ elements corresponding to the stable electronic configuration $6s^{2} 4f^{14} 5d^{10} 6p^{6}$.