Classification of Elements and Periodicity in Properties

Vocabulary flashcards covering historical periodic table developments including Doberenier's Triad, Newland Law of Octaves, Lother Maye Atomic Volume Curve, and Mendleep's Periodic Table.

Periodic Table

The arrangement of elements in groups in such a way that elements with similar properties are grouped together, with $118$ elements presently known.

Doberenier's Triad (1829)

An early element classification system whose limitation was that he could not arrange all the elements into triads.

Newland Law of Octaves

Stated by John Newland in $1866$ that when elements are arranged in order of increasing atomic masses, every $8\text{th}$ element has properties similar to the $1\text{st}$ element.

Limitations of Newland Law of Octaves

He could only arrange elements successfully till calcium (after which every $8\text{th}$ element did not possess the same property), and the later inclusion of noble gas elements disturbed the entire arrangement.

Lother Maye Atomic Volume Curve

A curve plotting atomic volume against atomic mass, establishing a relationship between physical properties and atomic masses of elements.

Peak Position on Lother Maye's Curve

Position occupied by the most electro-positive elements called alkali metals ($Li$, $Na$, $K$, $Rb$, $Cs$).

Descending Position on Lother Maye's Curve

Position occupied by less electro-positive elements such as $Ba$.

Halogens on Lother Maye's Curve

The most electro-negative elements ($F$, $Cl$, $Br$, $I$) occupying recurring positions on the atomic volume curve.

Groups in Mendleep's Periodic Table

The $9$ vertical columns named in Roman numerals ranging from $0$, $I$, $II$, $III$, $IV$, $V$, $VI$, $VII$, $VIII$, where groups $1$ to $7$ are divided into $A$ and $B$.

0-group

The group in Mendeleev's periodic table that contains inert gases.

Shortest Period

The $1\text{st}$ period in Mendeleev's periodic table, which contains $1$ element.

Short Period

The $2\text{nd}$ and $3\text{rd}$ periods in Mendeleev's periodic table, having $8$ elements each.

Long Period

The $4\text{th}$ and $5\text{th}$ periods in Mendeleev's periodic table, having $18$ elements each.

Longest Period

The $6\text{th}$ period in Mendeleev's periodic table, having $32$ elements.

Incomplete Period

The $7\text{th}$ period in Mendeleev's periodic table, so called because elements were still being discovered.

Mendleep's Periodic Law (1869)

States that the physical and chemical properties of the element are periodic functions of their atomic masses.

Mendleep's Argon-Potassium Adjustment

An adjustment where Argon with atomic mass $39.9$ was placed before Potassium with atomic mass $39.1$.

Ekalioron

The name given by Mendeleev to a gap left for an unknown element before it was discovered and named Scandium ("eka" means same).

Correction of Beryllium Atomic Mass

Beryllium was originally assigned atomic mass $13.5$ by multiplying equivalent mass $4.5$ by wrong valency $3$ (placing it between Carbon at $12$ and Nitrogen at $14$); correcting valency to $2$ gave atomic mass $4.5 \times 2 = 9$, placing it with Calcium and Magnesium in Group-2A.