Mendeleev and the Periodic Table

Vocabulary flashcards covering the principles of Mendeleev's periodic table, his use of atomic mass, predictions for undiscovered elements, and the transition to the modern table.

Dmitri Mendeleev

The scientist who developed the first periodic table of elements in $1869$ by organizing them based on atomic mass and chemical properties.

Atomic Mass

The physical property used by Mendeleev to arrange elements in increasing order, which was later replaced by atomic number in the modern periodic table.

Periodicity

The repeating pattern of chemical and physical properties of elements that occur at regular intervals when arranged by atomic mass.

Gaps

Spaces intentionally left in Mendeleev's periodic table for elements that had not yet been discovered.

Predictions

Mendeleev's forecasts of the specific characteristics and properties of undiscovered elements that would eventually fill the gaps in his table.

Gallium

An element predicted by Mendeleev as eka-aluminium, characterized as a shiny metal that melts in the hand and sits below aluminum.

Germanium

An element predicted by Mendeleev as eka-silicon, which is shiny like a metal but brittle like a non-metal.

Atomic Number

The property used to organize the modern periodic table, replacing Mendeleev's use of atomic mass.

$$63$$

The number of known elements that Mendeleev organized when he created his first periodic table.

Eka-aluminium

The name Mendeleev used for the predicted missing element located directly below aluminum in his periodic table.

Eka-silicon

The name Mendeleev used for the predicted missing element that forms compounds similar to silicon dioxide.

Lithium, Sodium, and Potassium

A group of elements used to demonstrate a pattern of properties; they are all soft and react with water.

$$1869$$

The year in which Mendeleev organized the known elements based on atomic mass and noticed periodic patterns.

Repeating Patterns

The observation that certain characteristics of elements reappeared periodically when elements were ordered by mass.